Cross-Platform Level Editor for Doom3 and The Dark Mod
Source port of Doom, Heretic, Hexen and Strife developed in Delphi
A Quake Live duel map veto system.
Quake Engine Map Viewer
Qreate is a sandbox mod/extension for id software's Quake.
A simple map launcher for Quake.
Export Quake maps from Blender 2.73+