Comprehensive Doom3 Tweak Guide
An Anonymous Coward writes "The folks at Techspot have a very comprehensive Doom3 Tweak Guide up. It will take you through every option available in the game, the console, config files, graphics, audio and input settings."
Very cool - as editing Doom 3's config files can give tremendous results. For instance, setting the following gave me a noticable boost (enabling me to go from 800x600 in medium quality to 1024x768 on high quality without loosing speed):
seta image_useCache "1"
seta image_cacheMegs "256"
seta image_cacheMinK "20480"