GAMA (GIS & Agent-based Modelling Architecture)
The “GIS and Agent-Based Modeling” blog reports on GAMA, an open source GIS-ABM tool that looks quite interesting:
GAMA is a simulation platform, which aims at providing field experts, modelers, and computer scientists with a complete modeling and simulation development environment for building spatially explicit agent-based simulations. It is being developed by several French and Vietnamese research teams under the umbrella of the IRD/UPMC International Research Unit UMMISCO since 2007.