RocketGuy has released a new mod called RQuake Team Cooperative.
It is an exciting new players versus the monsters mod by RocketGuy and is running at his server coop.runequake.com:26003
His server runs custom maps and it is virtually required that you have them (see the RQuake site for further information on that).
http://www.quakeone.com/rquake
And you probably have already noticed that the official forum is here at Rune Central. The prior version of this mod was known as Rune Quake Coop and this mod, like that mod, is based off the RuneQuake 1.0 source.