heh, for Doom I have like every source port- Zdoom, ZDaemon, GZDoom (current favourite) Doom Legacy, Doomsday with the JDRP... and GZScoreDoom, which I have to say is awesome if only for quadrupling the number of different enemies.
As well as the excellent "ObHack" program which can generate completely random levels. Works great with gzScoreDoom, as well as my DEH patch for changing maximum ammunition. Nothing like tossing a rocket into a crowd of over 50 zombies... or levels with over 400 enemies, more then half of them bosses...