NetLogo
NetLogo is fast becoming one of the main tools of choice for agent-based modelers. It grew out of an earlier project StarLogo, which was designed to teach ABM to primary school children. So it cannot be too difficult to learn! Over several years NetLogo has been further developed and extended and extensive support material added to become a major research tool for researchers developing ABM.
NetLogo is a multi-agent programmable modelling environment. It is used by tens of thousands of students, teachers and researchers worldwide. It is authored by Uri Wilensky, who is currently a professor of Learning Sciences and Computer Science at Northwestern University, and was developed at the Centre for Connected Learning at Northwestern University.
NetLogo programs can be ported into more comprehensive ABM platforms such as RePast.
NetLogo is freely available for use on MACs, PCs.
For further details go to the NetLogo website.