Wikipedia
Gajim
Gajim is an instant messaging client for the XMPP protocol which uses the GTK+ toolkit. The name Gajim is a recursive acronym for Gajim's a jabber instant messenger. Gajim runs on Linux, BSD and Microsoft Windows. Released under the GNU General Public License, Gajim is free software. A 2009 round-up of similar software on Tom's Hardware found version 0.12.1 "the lightest and fastest jabber IM client".