Mohawk Voice!

Mumble was the first and is the most successful and wide spread free and open source software for VoIP. It was the first VoIP software to provide low-latency audio suitable for gaming, and at the same time was a pioneer in high audio quality at the same time.

TeamSpeak is a proprietary Voice over IP software that allows users to speak on a chat channel with other users, much like a telephone conference call. A TeamSpeak user will often wear a headset with an integrated microphone. Users use the TeamSpeak client software to connect to a TeamSpeak server of their choice, from there they can join chat channels.The target audience for TeamSpeak is gamers, who can use the software to communicate with other players on the same team of a multiplayer game. Communicating by voice gives a competitive advantage by allowing players to keep their hands on the controls. »

Ventrilo is a real-time voice chat software for group communications with surround sound support.

Meeet.at is a free web voice chat solution that works without any plugins or registration all you need is a modern Browser (Chrome recommended). Creating a channel takes only 3 seconds you don't have to register or pay any special attention. Just klick on New Channel and the url you see in your Browserbar is your Voice chat channel.

Roger Wilco is a real-time voice chat technology that enhances communication among communities of users on the Internet. It allows you and your friends to talk to each other while playing multiplayer online games. It works with most existing games such as Quake III, Half-Life, and Diablo II. It is an unobtrusive companion technology that lets you talk to the other players instead of typing messages to them!