Try Trillian. It's also multi-client and can access AIM, MSN, Yahoo, etc
Watch with that though because AIM just blocked the TOC 1.0 protocol so anyone using that will be dropped. MSN and Yahoo! I can imagine MSN may do the same thing to try to control the viri and such that float around on it and Yahoo! may not though because of
honestly being such a small userbase they don't need to modify the protocol as often.