Psi is a free instant messaging application designed for the XMPP
network (including Google Talk). Fast and lightweight, Psi is fully
open-source and compatible with Windows, Linux, and Mac OS X.

With Psi's full Unicode support and localizations, easy file transfers,
customizable iconsets, and many other great features, you'll learn why
users around the world are making the switch to free, open instant
messaging.
