JRobots

IBM's Alphaworks: Robocode
Offers information, and downloads for Windows, Linux, and Mac.
http://www.alphaworks.ibm.com/tech/robocode/

Java Robots Home Page
Download, discussion and documentation.
http://www.mobydisk.com/java/jrobots/

Yahoo! Groups: javajousters
A group devoted to challenges among Java algorithms and Jrobots fights.
http://games.groups.yahoo.com/group/javajousters/