Digsby = IM + Email + Social Networks.
I have been using Digsby since its release and it gets better and better.
Digsby supports, Gmail, MSN, Yahoo, AOL, IMAP, and POP mail,
viewing Facebook, Myspace, Twitter and Linkedin without going the each of the sites is a real time saver.
The ability to add multiple IM accounts is wonderful, using AIM, MSN, Yahoo, Gtalk, Facebook chat, and others.
I cant think why you would want to use any other client. Can you?