Pidgin is an easy to use and free chat client used by millions. Connect to AIM, MSN, Yahoo, and more chat networks all at once.
Supported chat networks:
AIM
Bonjour
Gadu-Gadu
Google Talk
Groupwise
ICQ
IRC
MSN
MXit
MySpaceIM
SILC
SIMPLE
Sametime
XMPP
Yahoo!
Zephy