Ventrilo..

[Razoor]

Anyone that hosts a vent or know anyone that does? i need a room for my WoW guild :)

[Crille]

Mumble is free and better than Ventrilo ;)

[Farsa]

I've been using a free mumble server I got from ukgame for quite some time. Mumble is pretty awesome, although *some* people have problems with echo on it.
http://www.ukgame.com/voice_servers/murmur_mumble_voice_servers.html