This has got to be the best IM client ever used (better than
Pidgin IMO). It's also pretty customizable, with a lot of skins and
widgets.
With support for so many protocols, emails and even social
networking (not like I belong to any of the networks), this
rocks.
It's easy to use as well, best of all, FOC.
My only complain - I can't sort contacts by email. I looked
around hard but can't find it. 
Screenshot:
