Doomwire is a Lobby-driven Multiplayer client for Chocolate-Doom.

It provides players with a central point to set up multiplayer cooperative or deathmatch games (either LAN or Internet based)
aswell as an environment for players to chat.

Latest Beta: 0.2 Beta9
NOTE: You'll need the latest Chocolate-Doom to use Doomwire and you'll need to unblock a UDP port (default is: 2342) on your router if you are hosting games.
Chocolate-Doom is still under development, contact the Author (fraggle) if you find any bugs while using it.
Chocolate-doom - What Doomwire uses, great Doom port.
Odamex - Oldschool Multiplayer Client/Server Doom port, with cross-platform capabilities (Windows, Linux, BSD, MacOSX, Solaris)

Skulltag - Newschool Doom port for Windows

Unidoom - The most well known Doom clan ever.
Dwango United - They linked to me, so I'll link to them :P.

Doom News Sites:
Doomworld - The best Doom news site. (imo)
Deathmatch News - Site related to doom multiplayer, owned and operated by the z0r (deathz0r :P)
PlanetDoom - Another cool Doom site.

FreeDoom - A goal to create a completely free Doom Game (IWAD), so it can be used with Doom 2 PWAD files.
Doomworld /idgames - Probably the best place to get your wads from.
RareFiles - Oldschool doom site, started a long time ago, used to be THE download place for deathmatch wads for DoomServ.

Mancubus.net - Hosts this site.
Slipgate.org - The owner of slipgate is one of the first people I met on IRC
The Doom Wiki - Expand your Doom knowledge!