QWPython is a Python-powered QuakeWorld dedicated server. The core engine has been wrapped up as a Python module and altered to call back to Python to execute Quake game logic. A QuakeC - Python translator is also included, along with pre-translated versions of Deathmatch and Capture-The-Flag.
Sauerbraten (a.k.a. Cube 2) is a free multiplayer/single player first person shooter, built as a major redesign of the Cube FPS. Much like the original Cube, the aim of this game is not necessarily to produce the most features and eye candy possible, but rather to allow map/geometry editing to be done dynamically in-game, to create fun gameplay and an elegant engine.
ServerSpyIRC is a Perl IRC bot (based on Net::IRC) which can retrieve information about Quake2, Quake3, and Halflife/CS online game servers. It supports many search functions, scanning of posted IP addresses, simple clanwar outputs, user management, bookable functions, and server lists.