I've managed to get a Mumble server running on my VPS, feel free to use it 
184.22.118.104:64738
Registered.
Nobody's on it seems...
Ditto. It's funny, but it seems that a heck of a lot of gamers don't know stuff like this exists, or they know of only one program for it.
WoW players seem to know of Ventrillo only (*shudder*)
Many first person shooter fans seem to only know of TeamSpeak
Mumble, while seemingly gaining ground due to many of the more popular minecraft LPers using it, is still a relative unknown, which is too bad. IMO, it's the best cross platform (Windows, Linux, Mac) voice chat software anywhere.