BabyChess
Edit and play games on Unix or Windows, supports PGN, and FEN format. Includes a chess engine and client for ICS. [Open Source, GPL]
Dalek Chess
Includes news, downloads, and FAQ for an open source, animated Linux chess game using Doctor Who characters.
Egg Chess
Linux or Windows version involving eggs. [Open Source]
Hotbabe Chess
Freeware chess playing program with chatting and joking ability.
Maniac
Windows chess program that plays multiple variants of chess. Users may play with the computer or with other users on the Internet.
NagaSkaki
Windows version by Neels Groenewald with a computer opponent.
RDCHESS
Chess with a Windows GUI and most of the features of commercial programs.
YICS
Multiplayer software for using WinBoard, Xboard and other FICS interfaces to play on Yahoo! Chess.