Al Roth's Game Theory and Experimental Economics Page
This appears to be the most extensive list of game theory resources on the web.

The Prisoners' Dilemma
A good discussion of the Prisoners' Dilemma problem provided by Principia Cybernetica.

"Oligopoly and Interdependence in the Classroom" (by Margaret A. Ray, published in Classroom Expernomics)
An interesting example of the use of an oligopol like game in a classroom situation.