Ventrilo is the next evolutionary step of Voice over IP (VoIP) group communications software. Ventrilo is also the industry standard by which all others measure themselves as they attempt to imitate its features. Ventrilo can be used for home / personal applications like talking to friends and family, or playing organized online games where Voice Comm can make them more exciting and productive.
It can also be used in an enterprise environment as a productivity tool for conducting long distance group discussions. This would also help when using group collaboration programs that don't provide any kind of voice communication support.
A Ventrilo server could be setup in order to complement a web site that has voice interaction with its creators or for communicating with other people who share a common interest.