TeamSpeak 2
Teamspeak 2 is a voice chat application that lets you communicate with fellow players over the Internet. It also features a very basic text chat. The software consists of a client and a server, this way the communication channel is open all the time and players can freely join and leave in contrary to peer-to-peer software, e.g. skype.
Teamspeak is widely spread over the Internet and often comes with a game server. The sound quality is not very good and the latency is rather long. Another downside is the usage of the OSS (Open Sound System) instead of ALSA (Advanced Linux Sound Architecture) for sound processing. OSS doesn't support software mixing, in most cases you will need the the alsa-oss wrapper aoss that comes with ALSA to hear the sound of your game AND from Teamspeak.
Start Teamspeak with:
aoss teamspeak
If you play a game that also uses OSS (Older games for Linux, e.g. Enemy Territory) the same problem arises and you have to run that game with the alsa-oss wrapper too.
(this should work for most users but not for all :( )
If you run a 64bit system you need the 32bit version of aoss because Teamspeak binaries are 32bit only.

1 click install