New Doom - Your resource for everything to do with Doom, Doom II, and the new Doom!
Doom Center - The Gamer's Choice.
EDGE - EDGE (previously DosDoom) official homepage.
NTDoom - NTDoom homepage. Base of WDMP.
Team TNT - Creators of Boom, as well as many different Doom TCs/PCs (Including TNT and Plutonia, later released as Final Doom).