Iterated Prisoner's Dilemma - This site aims to be a comprehensive repository of information on the Iterated Prisoner's Dilemma, a major topic in artificial life, and a look at cooperation (and evolution of cooperation) between agents.Stanford Encyclopedia of Philosophy entry - This is a very complete description of the prisoner's dilemma and its variations.
Prisoner's Dilemma by the constitution web site - Some links on ethical and political aspect of the Prisoner's Dilemma.
The Taumoda Lab - This site offers a way to learn how to study the evolution of cooperation through 3 models, based on the Prisoner's Dilemma. (Java applets included).
Xerox PARC - This is a directory containing a lot of papers on Dynamics of Computation Area (Evolution of cooperation) from the XEROX PARC.
Robert Axelord and Lisa d'Ambrosio annotated bibliography - This is a very large annotated bibliography on paper on the Prisoner's Dilemma and furthermore on cooperation, written by Robert Axelrod and Lisa d'Ambrosio.
The Prisoner's Dilemma - A simple yet powerful model for the problem of cooperation versus conflict in groups. The JAVA applet demonstrates the spread of 'altruism' and 'exploitation for personal gain.'