A Google Talk client to call your Gmail contacts for free
Apple's official chat client for OS X
AstraChat is a lightweight Jabber (XMPP) stand alone client application that connects directly to your XMPP server without any proxy server in between.
SJ - jabber client with PGP encryption system, and much more
Messaging client for MSN, AIM, ICQ, Jabber, Yahoo and Gtalk
AstraChat is a standalone and lightweight Jabber (XMPP) client application with VOIP calling that connects directly to your XMPP server without any proxies in-between.
Light messenger client supporting ICQ, AIM, MSN y Jabber