Dragon Go Server is a web-based server for playing go (a.k.a baduk, weichi and igo). It's intended as a replacement for play-by-email, where the server keeps tracks of the moves. Tools used are php and mysql.
A PHP Web Application that you can install on your own web server. It allows you to play chess with other users across the internet or sitting at the same screen. It only permits valid moves and can automatically detect check and checkmate status.
netjatafl is a hnefatafl server and client system, allowing tafl players to join in networked games of tafl. Using a standard network protocol, new clients can be written for any platform. Clients in C++ and PHP/Javascript are included.
Javascript platform for tile map based single/multiplayer games with both off-line and server-based play modes. Try it out right away at http://tilescape.hg.sf.net/hgweb/tilescape/raw-file/tip/js/game.html
Chessd is a chess XMPP based server. It uses a web interface and a BOSH server, that runs between interface and the chess server. Visit http://xadrezlivre.c3sl.ufpr.br to see it in action.