Individual-Based Models

http://www.red3d.com/cwr/ibm.html
an annotated list of links
by Craig Reynolds

Individual-based models are simulations based on the global consequences of local interactions of members of a population. These individuals might represent plants and animals in ecosystems, vehicles in traffic, people in crowds, or autonomous characters in animation and games. These models typically consist of an environment or framework in which the interactions occur and some number of individuals defined in terms of their behaviors (procedural rules) and characteristic parameters. In an individual-based model, the characteristics of each individual are tracked through time. This stands in contrast to modeling techniques where the characteristics of the population are averaged together and the model attempts to simulate changes in these averaged characteristics for the whole population. Individual-based models are also known as entity or agent based models, and as individual/entity/agent-based simulations.

Some individual-based models are also spatially explicit meaning that the individuals are associated with a location in geometrical space. Some spatially explicit individual-based models also exhibit mobility, where the individuals can move around their environment. This would be a natural model, for example, of an animal in an ecological simulation. Whereas plants in the same simulation would not be mobile. Some individual-based models are not spatially explicit, for example a simulation of a computer network might be based on individual models of the networked computers, but their location would be irrelevant. Spatially explicit models may use either continuous (real valued) or discrete (integer valued, grid-like) space.

Individual-based models are a subset of multi-agent systems which includes any computational system whose design is fundamentally composed of a collection of interacting parts. For example an "expert system" might be composed of many distinct bits of advice which interact to produce a solution. Individual-based models are distinguished by the fact that each "agent" corresponds to autonomous individual in the simulated domain.

There is an overlap between individual-based models and cellular automata. Certainly cellular automata are similar to spatially-explicit, grid-based, immobile individual-based models. However CAs are always homogeneous and dense (all cells are identical), whereas a grid-based individual-based model might occupy only a few grid cells, and more than one distinct type of individual might live on the same grid. (Of course a CA can have cells in various states, and so represent concepts like empty or occupied by type 3. Perhaps the significant difference is whether the simulation's inner loop proceeds cell by cell, or individual by individual. (Although that distinction is muddied by parallel-processing hardware.)) The philosophical issue is whether the simulation is based on a dense and uniform dissection of the space (as in a CA), or based on specific individuals distributed within the space.

Of course, note that everyone uses terminology differently, so take the definitions above with a grain of salt. ("Your mileage may differ.")

My interest in this area began when I made a model of bird flocks and related group motion. As a result I am particularly interested in individual-based models using spatially explicit mobile agents in continuous space. This bias may be reflected in the selection of resources listed below.

Online resources

These are general purpose software toolkits useful for implementing individual-based models.
Swarm is a software package for multi-agent simulation of complex systems originally developed at The Santa Fe Institute and now at the Swarm Development Group (SDG). See this preliminary version of the Swarm FAQ and these example applications built using the Swarm system.
Echo, conceived by John Holland, is a ecology simulation framework, whose individuals live in a discrete spatially-explicit world and evolve according to a genetic algorithm. See Modelling Complex Adaptive Systems with Echo (1995) by Terry Jones and Stephanie Forrest
XRaptor (A Simulation Environment for Continuous Virtual Multi-Agent Systems) by Günter Bruns, Peter Mössinger, Daniel Polani, René Spalt, Thomas Uthmann and Stefan Weber.
Listed below are applications of individual-based models, arranged by general topic area.
Ecology and Biology:
Mixed ecosystems
ATLSS Across Trophic Level System Simulation for the Everglades/Big Cypress Region of South Florida, a very large-scale ecological simulation effort lead by Donald DeAngelis and a cast of thousands. See the related paper: Computational Models of White-Tailed Deer in the Florida Everglades, and this report from Science Alliance News.
Facilitating Mobile Objects within the Context of Simulated Landscape Processes by James D. Westervelt and Lewis D. Hopkins this 1996 paper describes modeling carnivore and herbivore populations as they interact with vegetation in the context of a landscape described with a geographic information system.
Evolution and Spatial Structure Interact to Influence Plant-Herbivore Population and Community Dynamics by Gregg Hartvigsen and Simon Levin. An individual-based model of plant-herbivore interactions and coevolution.
Insect/Plant Interactions Program by Peter Room, Jim Hanan, et al., models growth of individual plants, either singly or in small stands, and interactions with individual insects as they crawl on or fly between the virtual plants.
A Multimodeling Basis for Across-Trophic-Level Ecosystem Modeling: The Florida Everglades Example (1997) by Paul Fishwick, James Sanderson and Wilfried Wolff.
The implementation and visualisation of a large spatial individual-based model using fortran 90 (1996) by Tim Hopkins and David R. Morse. A simulation of the spread of Barley Yellow Dwarf Virus in a barley field, the model considers explicitly each individual plant and aphid.
Fish
Development of a spatially explicit, individual-based model of marine fish early life history by Sarah Hinckley, Albert J. Hermann, and Bernard Megrey, published in Marine Ecology Progress Series. See also Individual-based modeling of walleye pollock in the southeast Bering Sea. And see Ocean Current Model Shows Where Larvae Drift in the ARSC newsletter. See also animation links on A Biophysical Model of Shelikof Strait.
Individual-Based Fish Population Model Applied to Management Issues (1991) Deangelis et al., individual-based population model for smallmouth bass, used to investigate the impact of varying the opening date of the fishing season.
The EPRI CompMech Program: Compensatory Mechanisms in fish populations (at the Electric Power Research Institute, of the Environmental Sciences Division at Oak Ridge National Laboratory). See the software directories containing individual-based models of chinook and trout.
Individual-Based Approach to Analyzing PIT-Tag Data (1997) modeling of migrating salmon based on data from passive transponder (PIT) tags. Contractor technical contact: Kenneth A. Rose
Individual-Based Fish Modeling in the Mathematical Modeling Program at Humboldt State University by Roland Lamberson with Steve Railsback and Steve Jackson
NerkaSim by James Scandol et al. uses individual based models of the migration of salmon. See this snapshot of a simulation run.
Development of an Individual-Based Trout Instream Flow Model (1999) by Russell B. Rader and N. LeRoy Poff
Mammals
Gorilla Simulation work by Mark Scahill including this update and a draft paper called Modeling Mountain Gorillas from around 1995.
Spatially Explicit Population Dynamics and the Snowshoe Hare by Jason A. Thomas. See also his list of links on Spatially-Explicit Population Modelling and Spatial Ecology Modelling and Analysis Software.
Model of Animal Behavior (MOAB) a description of software for a spatially explicit, individual based model of animal movement and foraging behavior by Jacoby Carter and colleagues at the U.S. Geological Survey. See also this poster paper (with illustrations): MOAB: A Spatially-Explicit, Individual Based, Expert System for Creating Animal Foraging Models
PUMA software by Paul Beier was developed to predict the risk of extinction in cougar populations under various development scenarios. The model is individually-based but not spatially explicit
Deer Management Simulator by Ken Risenhoover (et al.?) is a spatially explicit modeling environment for evaluating deer management strategies. See also these summaries of related research at the same lab.
Aggregation and the Emergence of Social Behavior in Rat Pups Modeled by Simple Rules of Individual Behavior (1998) by Jeff Schank (see also) and Jeffrey Alberts models huddling in infant Norway rats.
Birds
The Weaver Project by Matt Hare, Alan Sibbald, and Alistair Law, is a spatially explicit, individual-based model of the red grouse in Scotland's heather moorland. It seeks to provide wildlife managers with advice on appropriate strategies to restore grouse populations.
Multiscale Dynamic Simulation for Ecological Modeling by Pedro Pereira Gonçalves and Maria Paula Antunes studies environmental spatial heterogeneity and the reactions of individual organisms. The system is integrated with a Geographical Information System package enabling the interactions of virtual objects with real data. Includes a model of flocking birds.
Channel Island bald eagle and peregrine falcon populations (1994?) by Gordie Swartzman
Development of a spatially-explicit, individual-based model to simulate Kirtland's Warbler population dynamics (1998) by Carol Bocetti et al. at USGS PWRC.
Insects
Multi-Agent Simulation of Honey Bee Colonies by David Sumpter uses a Swarm-based model to investigate colony activities (particularly thermoregulation) by simulating bee behavior.
Manta by Alexis Drogoul is an ethological simulation of ant colony behavior modeled at the level of individual ants. Several related papers are available online. See also this review of Manta by Howard Gutowitz.
The non-linear dynamics of survival and social facilitation in termites by Octavio Miramontes and Og DeSouza. Uses a "mobile cellular automata" (a mobile, spatially explicit individual-based model in discrete space) to simulate a colony of termites. See also Miramontes' Complexity and Social Behaviour.
An Individual Tree Based Model of Mountain Pine Beetle Invasion (1999) by Emily Stone
Carl Anderson uses agent-based models to study the organisation of workers and work in insect societies and related regulatory mechanisms, particularly task partitioning and self organization in ant and bee colonies. Some papers are avaialble at his older web site.
Forests
Scaling from Trees to Forests: Analysis of a Complex Simulation Model by Doug Deutschman, Simon Levin, Catherine Devine and Linda Buttel. (A very nicely produced multimedia presentation in Science Online.) Spatially explicit forest growth models using SORTIE, a stochastic individual-based simulation model of forest dynamics in which trees compete for light. (See also these SORTIE forest images.)
Arborgames by Melissa Savage and Manor Askenazi examines the role of forest fire on species diversity. Local interaction of trees in a neighborhood allows the model to generate complex landscape dynamics. Bruce Sawhill is collaborating on analysis of model results. Robert Bell is working on a application in Yellowstone.
SmartForest An interactive forest visualizer, by UIUC's Imaging Systems Laboratory, models forest management issues at the level of the individual trees. The software is available for download.
Marine Invertebrates
Ship Fouling by Yosef Cohen. A Java applet demonstrating the interaction of barnacles settling on the hull of a ship and limpets, used as a biological control, which can bulldoze away young barnacles.
A virtual mesocosm with artificial salps for exploring the conditions of swarm development in the pelagic tunicate Salpa fusiformis (1997) Philippe Laval in Marine Ecology Progress Series Volume 154
Arachnids
Mites IBM applet by Nils Kösters at the German Life Sciences Information service. Simulation of the life and times of a breeding population of mites. See also this other copy (?) and this 3D version.
Bacteria
BacSim, a simulator for individual-based modelling of bacterial colony growth (1998) by Jan-Ulrich Kreft, Ginger Booth and Julian Wimpenny. BacSim is based on Gecko, which is based in turn on Swarm
Non-species-specific models, and other topics
The Tragedy of the Commons Java applets and commentary by Walter Korman (from the now defunct weekly column Deep Magic). Based on Garrett Hardin's 1968 paper.
Parallel Software Tools for Ecological Simulation including the Java-based GUST which runs an interactive version of their Szymanski-Caraco cellular automata model. See their Guide to Related Research.
Ecomachines and Spatial Modeling in Ecology and Biology was a workshop held January 13-16, 1996 at the Santa Fe Institute.
Gecko, a spatial individual-based simulator for modeling ecosystem dynamics, by Oswald Schmitz and Ginger Booth.
ECOTOOLS uses individual-based models to study animal behavior and ecological issues. See descriptions of various ECOSIM reimplemented models: schooling, flocking, storks, dragonflies, crowns, largemouth bass, northern cod.
Theoretical Ecology of Spatial Heterogeneity: An IBM Approach ongoing work by Kim Cuddington on "...the effects of limited mobility and spatial structure or heterogeneity on the population dynamics and stability of communities." See also these resources on theoretical ecology.
Methods, Conceptions & Ideas on Ecological Modelling by Andrey Tsyplianovsky. This extensive site covers many aspects of ecological modeling and includes a comprehensive list of links on individual-based models.
Ten years of individual-based modelling in ecology: what have we learned, and what could we learn in the future? (1999) by Volker Grimm in a special issue of Ecological Modelling on Individual-based models.
Forager, from Amber Waves Software, simulates foraging (feeding behavior). Users can set up animal behavior models, graphically design the foraging environment and specify behavior rules.
Papers from the Third International Conference/Workshop on Integrating GIS and Environmental Modeling January 21-25, 1996, Santa Fe, New Mexico:
Individual-Based Models in Ecology: An Overview by Donald L. DeAngelis, D. M. Fleming, L. J. Gross, and W. F. Wolff,
Some Guidelines For Implementing Spatially Explicit, Individual-Based Ecological Models Within Location-Based Raster GIS. by Roger L. Slothower, Paul A. Schwarz, and Kevin M. Johnston
Spatial Modeling of Aquatic Habitat From a Fish's Perspective by John K. Horne, J. Michael Jech, and Stephen B. Brandt
From Individuals to Populations, papers from a 1998 International Workshop and Young Scientists School held in Ceske Budejovice, Czech Republic:
On individual-based models for single-species population growth, predator-prey interaction and optimal foraging
Individual behaviour and population dynamics: a protocol for extracting population growth rates from individual-based models
An individual-based model of mite predator-prey populations: local dynamics
From individuals to population in parasitoid-host and predator-prey models
Biola: a new biological programming language for developing individual based models
Instructional Tools:
EcoBeaker by Eli Meir is an ecological simulation program, designed for use by students in the classroom.
The Virtual Forest by EcoLogik and BeakerWare
Individual-based ecological models: Spatial models for undergraduate investigation by Louis J. Gross
Modeling Humans (and Artificial Societies)
Human Crowds: motion and psychology
An Agent Based Simulation Environment for Public Order Management Training by Roderick Williams is a tool to help train training police officers to manage large public gatherings (crowds, demonstrations, marches). See also the page for the CACTUS (Command And Control Training and Planning Using Knowledge Based Simulation) system.
Legion by G. Keith Still is used to simulate the motion of large crowds of people. It can handle crowds of more than 100,000 people.
Animation Science Corporation sells tools to model the motion of large crowds with their Rampage software, based on an efficient engine for interacting particle systems.
EINSTein (Enhanced ISAAC Neural Simulation Toolkit), an artificial-life laboratory for exploring self-organized emergent behavior in land combat, by Andy Ilachinski of the (US) Center For Naval Analyses.
The Collective Action Project by Clark McPhail and John McCarthy, studies individual and collective actions of people in large temporary gatherings (crowds, mobs, demonstrations). See also A Computer Simulation of a Sociological Experiment (1995) by David Schweingruber based on the GATHERING simulation written by William T. Powers, based on Perception Control Theory.
An Agent-Based Model of Seating In A Theater a Java-based class project by Yale Wang. See also his version of Schelling's Segregation Model and the El Farol problem: how the appropriate number of people decide to show up for an event.
Modeling Audience Group Behavior by Nuria Oliver and Stephen Intille describes an agent based model (spatially explicit, discrete space, non-mobile) of synchronization and other decentralized collaborative behaviors of a group audience.
Anthropology
Swarm-based Modeling of Prehistoric Settlement Systems in Southwestern North America (1997) by Tim Kohler and Eric Carr, describes an agent-based simulation constructed with the Swarm system. See also this 1995 paper: Agent-Based Modeling of Anasazi Village Formation in the Northern American Southwest.
Computational Anthropology: The Simulation and Representation of Bio-Cultural Processes, a section of the American Anthropological Association.
The Cultural Transmission Project studies population structure, cultural transmission, and evolutionary theory. Some of its research involves individual-based models, such as the use of Swarm in Building Expectations for "Wasteful" Behavior among Human Populations.
Culture Group Meeting: Agent-Based Modeling of Small-Scale Societies report on summer 1998 meeting at SFI.
Artificial Societies
Sugarscape (and the book Growing Artificial Societies: Social Science From the Bottom Up) by Joshua M. Epstein and Robert Axtell. Describes experiments with an artificial society, a computer model consisting of a population of autonomous agents and a separate environment in which the agents live. See also this Discovery Online feature and this Science News article.
Artificial Societies and Psychological Agents (abstract, 1996) by Stuart Watt (see also the full paper in PDF format) towards the development of "psychological agents" better suited for interaction with humans.
Sociology
Simulation: a emergent perspective, text of a lecture advocating use of individual-based models in sociology and related fields, by Nigel Gilbert. See related material at The Computer Simulation of Societies site.
Agency and Interaction (PDF 171K) by Peter J. Burke considers the connection between macro-level group characteristics (social structure) and the micro-level interaction between individuals.
Interpersonal Communication
Coordinating Turn-Taking with Gaze by David G. Novick, Brian Hansen and Karen Ward. Uses an individual-based model to validate the proposed mechanism.
Formal Approaches to Innate and Learned Communication: Laying the Foundation for Language (1997) by Mike Oliphant. Identifies the conditions necessary to establish a system of communication in a population of individuals, whether through evolution or learning.
Emotion
New Fungus Eater Experiments by Thomas Wehrle describes a multi-agent framework for investigation of the psychology of emotion, based on a model proposed by Masanao Toda.
Emotional Intelligence in Multi-Agent Simulation (1998) by Eric Werk, on designing believable agents.
other topics
Theory in a Complex World: Computational Laboratories in Economic Geography by Catherine Dibble explores the gap between simulation experiments and a understanding of the underlying phenomena.
Spatially-Explicit Autonomous Agents for Modelling Recreation Use in Complex Wilderness Landscapes by Randy Gimblett, Bohdan Durnota and Bob Itami, uses autonomous agents to assist natural resource managers in assessing and managing dynamic recreation behavior, social interactions and resulting conflicts in wilderness settings. See also the Recreation Behavior Simulator (RBSim) which simulates the behavior of human recreators in high use natural environments.
Rational Actors Versus Adaptive Agents: Social Science Implications (1998) by Paul E. Johnson. A comparison of two research methods, "rational choice theory" and "agent-based modeling." Is agent-based modeling really different and is it really better? Johnson says the answers are "yes" and "sometimes"... Uses SWARM. (Figures are here.)
CORSIM is a microsimulation model of individual and family behavior through time. See the paper Dynamic Microsimulation and the CORSIM 3.0 Model (1993) by Steven B. Caldwell, and this list of current research projects.
The Uses of Sim Sidewalks an essay by Steven Johnson in FEED Magazine: "What happens when urban scholars sit down to play SimCity?"
Economics
Playing the game of life by Rita Koselka (an April 7, 1997 article from Forbes) covers individual-based models of the music CD business by the Emergent Solutions Group of PricewaterhouseCoopers, the stock market by W. Brian Arthur and John Holland, the Sugarscape model by Joshua Epstein and Robert Axtell, and Challenge from Thinking Tools.
Aspen, a microanalytic model to simulate the U.S. economy. Aspen uses economic agents to represent the various decision-making segments, and the microanalytic simulation process models each agent individually. See also this earlier press briefing.
Agent-Based Computational Economics (ACE) by Leigh Tesfatsion, a computational study of economies modeled as evolving decentralized systems of autonomous interacting agents. Which seeks to explain these global regularities in economic processes from the bottom up. See also How Economists Can Get Alife: Abbreviated Version
Agent based simulation of artificial electricity markets by Raimo P. Hämäläinen et al. models how customers respond to different price patterns for electrical power.
Artificial Life Simulation of the Textile/Apparel Marketplace: An Innovative Approach to Strategizing about Evolving Markets by Evelyn L. Brannon, Lenda Jo Anderson, R. Alan Donaldson, Thomas E. Marshall, Pamela V. Ulrich.
Economic Modeling of Global Innovation Diffusion, Diploma Thesis of Johannes Kottonau and Friedemann Buergel (aka Bürgel) uses an agent based simulation model called LEM 1.1 to visualize cultural, institutional, economic and legal key factors of spacio-temporal diffusion of new technologies (specifically Light Electric Vehicles (LEVs)).
Agent Based Simulation of the Hotelling Game by Michael Friedlander and David Sumpter a spatial variation on a model of the pricing of identical goods by the only two shops in a town.
Market Organisation by Gerard Weisbuch , Alan Kirman and Dorothea Herreiner, also available as SFI working paper 95-11-102.
Traffic and vehicle simulations
Hank is an interactive automotive driving simulation with an individual-based model of autonomous vehicle traffic and pedestrians. These provide the dynamic environment and allow authoring scenarios. By Jim Cremer, Joe Kearney and the Hank Team.
MITSIM A Microscopic Traffic Simulator for Evaluation of Dynamic Traffic Management Systems developed at MIT's Intelligent Transportation Systems lab by Qi Yang and Haris N. Koutsopoulos
Microsimulation of road traffic a very nice Java applet demonstrating a continuous "microscopic" model of traffic dynamics in several scenarios by Martin Treiber and Dirk Helbing. See also Discrete Force Model for Pedestrian Motion Java applets by Kai Bolay and Dirk Helbing.
Stop-and-Go Science (1999) by Peter Weiss in Science News Online. Survey article: "by better understanding traffic flow, researchers hope to keep down highway congestion."
Transportation Analysis and Simulation System at the Los Alamos National Laboratory. "TRANSIMS models a metropolitan region with a representation of the inhabitants, their activities, and the transportation infrastructure. TRANSIMS then simulates the movement of individuals across the transportation network, including their use of vehicles such as cars or buses, on a second-by-second basis."
Smartest Project (Simulation Modelling Applied to Road Transport European Scheme Tests) by Ken Fox. See also these lists of traffic micro-simulation links and abstracts.
The STEER Traffic Simulator (Signals/Traffic Emulator with Event-based Responsiveness) is a program intended to simulate traffic on an urban network, modeling up to tens of thousands of vehicles.
METROPOLIS 1.0 is a modular system for Dynamic Traffic Simulations: It is aimed towards on-line as well as off-line simulations of traffic flows in an urban context and for large networks.
SmartPath simulation and animation package for traffic studies. See also Smart AHS a specification, simulation and evaluation framework for modeling, control and evaluation of Automated Highway Systems (AHS). Both part of California's PATH (Partners for Advances Transit and Highways)
Demonstration of Traf-Netsim for Traffice Operations Management: Final Report (1991) by Joan D. Sulzberg and Michael J. Demetsky. A "microscopic level" simulation of cars, buses and pedestrians.
Elevator Demos an individual-based simlulation model of a set of elevators in a ten story building. Uses a Java applet graphical front-end and a MODSIM III back-end running on a remote server.
Animation and Interactive Multimedia
The boids model of coordinated group motion such as flocks, herds and schools by Craig Reynolds. See also these demos of other related steering behaviors.
Artificial Animals for Computer Animation: Biomechanics, Locomotion, Perception, and Behavior (Ph.D Dissertation, 1996) by Xiaoyuan Tu. A biologically plausible, physically based model of fish ethology at the individual level.
The Virtual Fishtank is an interactive museum exhibit developed (by The Computer Museum, MIT Media Lab, and NearLife Inc.) to introduce visitors to the phenomena of emergence and ideas from the sciences of complexity. See also these pages about The Virtual Fishtank at MIT and NearLife.

Related topics
Stochastic Spatial Models: A Hyper-Tutorial by Rick Durrett covers stochastic spatial models and their applications to biology.
Annotated list of links related to metapopulation biology, spatial population biology, landscape ecology by Dag Hjermann
Distributed Modular Spatial Ecosystem Modeling by Thomas Maxwell and Robert Costanza of the International Institute for Ecological Economics, and see the related Spatio-Temporal Modeling Page
WWW-Server for Ecological Modeling at the University of Kassel
A Multiple-Mechanism Developmental Model for Defining Self-Organizing Geometric Structures (1995) by Kurt Fleischer simulates the self-organization of structures in space at the level of individual "cells". See some images from this work.
MOSAIC: Simulation Modeling and Analysis of Cellular Interactions (warning, that is a traslation of the subtitle by a non-French-speaking American (me)).
Internet Ecologies Area at Xerox Palo Alto Research Center
Multi-robot systems:
Many-Robot Systems a US Navy site with a collection of papers about systems involving multiple robots. Explores collective action, cooperation, communication and self-organization.
Intelligent Methods for Multi-Agent Environments (1997) by Cem Ünsal. Presentation on self-organization and cooperation in natural and robotic groups.
Self-Organization in Large Populations of Mobile Robots (1993) by Cem Ünsal. Describes the use of a homogeneous population of robots, an Army-ant swarm, for transportation of material.
The Ants: A Community of Microrobots and their social behavior
The Amorphous Computing group at MIT explores issues such as "How do we obtain coherent behavior from the cooperation of large numbers of unreliable parts that are interconnected in unknown, irregular, and time-varying ways?"
Co-ordination in Artificial Agent Societies Social Structures and Its Implications for Autonomous Problem-Solving Agents (1999) by Sascha Ossowski
Microsimulation links at CRESS Centre for Research on Simulation in the Social Sciences
Mirror Worlds: Or the Day Software Puts the Universe in a Shoebox...How It Will Happen and What It Will Mean (1991) by David Gelernter. See also this bio of Gelernter and this review of Mirror Worlds in CTHEORY.
Web-Based Simulation links by Paul Fishwick, and A Survey of Web-Based Simulation by Ernie Page
Offline resources

Books
Individual-Based Models and Approaches in Ecology: Populations, Communities and Ecosystems, by Donald L. Deangelis, Louis J. Gross (Editors), published in 1992 by Chapman and Hall.
The Complexity of Cooperation: Agent-Based Models of Competition and Collaboration by Robert Axelrod, published in 1997 by Princeton University Press. See also this online supplement.
Simulating Organizations: Computational Models of Institutions and Groups (1998) edited by Michael Prietula, Kathleen Carley and Les Gasser.
Turtles, Termites, and Traffic Jams Explorations in Massively Parallel Microworlds (1997) by Mitchel Resnick
How Hits Happen--Forecasting Predictability in a Chaotic Marketplace (1998) by Winslow Farrell, with foreword by Brian Arthur. Using agent-based models to simulate the consumers of pop culture. Find it at Amazon.com or ACSES.
Laboratories and Groups

Academic
Dynamic Landscape Simulation Modeling group of the Geographic Modeling Systems Laboratory at UIUC. See the page on Dynamic, Spatial, Ecological Modeling with links to spatially explicit models related to birds at Fort Hood, the desert tortoise, and a quasi-individual-based model of the sage grouse.
ECOTOOLS (and WESP) at the University of Oldenburg, develop tools to support the modeling and simulation of individual-oriented ecological models.
Wildlife Habitat Analysis Lab of the Department of Wildlife & Fisheries Sciences at Texas A&M University. See these Research Summaries.
Center for Computable Economics at University of California, Los Angeles. See for example Agent Based Simulations as a tool in Economics.
The Sony Computer Science Laboratory Paris has a research project on evolutionary linguistics which make use of indivudual-based models to study the emergence of language and meaning.
Project for the Simulation of Social Behaviour within the Italian National Research Council - Institute of Psychology. Within this program, formal models of interactions among intelligent autonomous agents have been developed and some computer simulation studies have been conducted.
Centre for Policy Modelling at Manchester Metropolitan University, especially the Special Interest Group on Agent Based Social Simulation.
Commercial
The Emergent Systems Group of PricewaterhouseCoopers uses multiple agent systems to model decision making and trends in various simulations of real world marketplaces. See Flight Simulators for Management (BusinessWeek 1998: "computer models may give execs previews of how decisions pan out") and Playing the game of life (Forbes 1997).
Thinking Tools uses Agent Based Adaptive Simulation technology to create the management equivalent of flight simulators to help train business decision-makers on a risk-free "practice field". An early project was TeleSim.
Journals

Journal of Artifical Societies and Social Simulation (JASSS)
Conferences

Past
Economic Simulation Conference Conference Proceedings February 9-10, 1996.
From Animals To Animats (SAB98) Fifth International Conference of the Society for Adaptive Behavior, University of Zurich, August 17-21 1998, Zurich, Switzerland.
Sixth International Conference on Artificial Life (Alife VI) June 27-29, 1998, University of California, Los Angeles, USA.
Multi-Agent Systems and Agent-Based Simulation (MABS 98) one of the eight meetings (including Third International Conference on Multi-Agent Systems (ICMAS 98)) comprising Agents' World
First International Conference on Virtual Worlds, July 1-3, 1998, International Institute of Multimedia, Paris, France.
Local Interaction and Global Phenomena in Vegetation and Other Systems, April 19-23, 1999, Institute for Mathematics and its Applications, University of Minnesota
Future
Workshop on Traffic and Granular Flow '99, September 27-29, 1999, University of Stuttgart, Germany.