Trillian is a skinnable, interoperable instant messaging client. It connects to all the major chat networks, including AIM, MSN, ICQ, Yahoo! and IRC. Trillian .74 is completely free, with no spyware and no ads. Users of Trillian 0.74 should apply patch I to address a recently discovered security vulnerability.
Screenshot: 
Download: Trillian Basic 0.74i | Patch I for users of Trillian 0.74
View: Cerulean Studios
News source: Tech-Critic
