Artificial Life, Artificial Law

Gene Pool for Windows. - Gene Pool is an artificial life simulation where populations of physics-based organisms evolve over time.
Hardware Artificial Life (HAL) - Lotus Artificial Life's Java cellular automata substrate capable of supporting evolving, self-reproducing organisms which are capable of universal computation.
Java, Artificial Life, and creature behaviour - Java application simulates creature behaviours and movement. Available for free download, including source code, and a paper on Artificial Life.
John Holland's ECHO - Echo is a simulation tool developed to investigate mechanisms which regulate diversity and information-processing in systems comprised of many interacting adaptive agents, or complex adaptive systems (CAS).
JuhasWorld - JuhasWorld: Yes it's alive! You have to see this applet to believe it. Just let those actors evolve for a few generations and they suddenly seem quite clever indeed. Wait a few more generations and you will be completely hooked: How good can they get?
Keith's Artificial Life - An extensive collection of macintosh alife programs fitting into genetic algorithms, large swarms, evolutionary simulations, complex neural networks, and other related subjects.
Manna Mouse - Exploration of fitness landscapes.
Mirek's Cellebration, 1D and 2D Cellular Automata viewer, editor and explorer - A collection of information relating to cellular automata.
Nepros Homepage - Simulation of robots controlled by neuronal nets. They are learning their behvour by means of neuro-evolution
PolyWorld Information (author's site) - Source of information, technical report, and source code for the PolyWorld computational ecology, maintained by Larry Yaeger, PolyWorld's author. (This site contains more up to date links and information than the PolyWorld page at the Santa Fe Institute site.)
Polyworld Information (Santa Fe Institute) - PolyWorld ecological simulator, designed and written by Larry Yaeger.
Red Bird Island Productions - Simple world with automata that act to form complex systems. Implimented on the Macintosh.
Share-A-Life - Share-A-Life can be used to design experiments in which variables are manipulated and one measure the effects of these manipulations, to test hypotheses, and collect data to be compared with real data. Althought Share-A-Life is an educational tool it can also be used as a game.
The Swarm Simulation System - The Swarm Simulation System
The Virtual FishTank - Designed for people of all ages, the FishTank offers firsthand experiences in creating artificial life forms and reveals how simple behavioral rules can produce complex and surprising results.
Tierra home page - One of the first and the most influencial artificial environments created originaly by Tom Ray.