Links
First place to visit if you want to start to play Quake 2 immediately http://q2s.tastyspleen.net/
If you want to find other players, try to make own maps, own mods or dig into Quake 2 source code, this is a place to visit.
Forum of active players and positive people, here you can find answers for questions (not necessarily related to Quake 2) and download stuff, and play Quake 2.
A bit sleepy, but a fine place for Quake 2 enthusiasts.