envbot is an advanced modular IRC bot coded in bash. Features include SSL, IPv6, modularity (with several good modules already), transport modules (including OpenSSL, GnuTLS, netcat, etc.), loading/unloading/reloading of modules at runtime, rehashing configuration at runtime, advanced access control, and much more.
SuperTux is a side-scrolling platform game. The hero in this game is Tux the Penguin, the game's only reference to Linux. On the journey to rescue Penny, who has been kidnapped by evil Nolok, Tux faces 23 different kinds of bad guys while jumping and running through 101 beautifully-drawn levels. The soundtrack is available on last.fm and similar sites.