Pidgin is a multi-protocol Instant Messaging client that allows you to use all of your IM accounts at once.
Pidgin can work with:
* AIM
* Bonjour
* Gadu-Gadu
* Google Talk
* Groupwise
* ICQ
* IRC
* MSN
* MySpaceIM
* QQ
* SILC
* SIMPLE
* Sametime
* XMPP
* Yahoo!
* Zephyr