YAACT (Yet Another Anti Cheat Tool) is an anticheat tool developed for Counter-Strike. The Master-Server, Anticheat Server, Client construction also allows support for other games in the future.
YuGiOh Card Duelist Scoreboard As it's name says it is a scoreboard for duels of YuGiOh cards.
Kit for Game Developers Resources for game tools and tutorials at http://www.euclideanspace.com/software/games/twod/
The only LOK server emulator in production. Being developed in C++ based off of multiple open source rpg's (Crossfire, for example). 2D top-down game with a lot of history and a great community.
The Free Show is a real time, chat-like, telepathic-like 3D Game Environment consisting primarily of Humour. You can go to http://www.thefreeshow.eu to read this SDK of a 3D Game/Chat Environment.