- Major Sites:
DooMWorld - The hub of the DooM community, including news and forums.
Ledmeister's ClassicDooM - The first and last word on how to DooM.
BahdKo's DooM2.net - A very comprehensive DooM deathmatch site.
Compet-N - The original DooM speedrunning competition.
IDOOM Contest - A competition with multiple rounds comprising a season, where each round has a different objective.
Public DANG - Demo Archive of the Non-Gods. Sort of the poor man's Compet-N. Died in 2003.
Tool-Assisted Speedruns - The site that began the TAS phenomenon. Dead.
- PWAD Demos:
LMPS R' US - Jason Henry's great demo archive. Died in 2000.
Team Insanity - A good contest site. Died in 2001.
- Source Ports:
PRBoom+ - Supports Boom/MBF extensions and accurately emulates the original EXE. Includes TAS features.
DooM Legacy - Enhanced port with 3D floors, TCP/IP netplay, scripting.
ZDoom - Enhanced port with slopes, particles and extensive scripting support.