Also if Colloquy isn't your thing, there's also LimeChat and Linkinus. I've got lots of bitching that Colloquy's a dead project (with commits from a day ago...) and people who decide to switch have found those two clients to be useful, although Linkinus is shareware.
Also you might want to try building from svn, I've got some builds up on http://janeylicious.com/colloquy/ if you're interested.
Also if Colloquy isn't your thing, there's also LimeChat and Linkinus. I've got lots of bitching that Colloquy's a dead project (with commits from a day ago...) and people who decide to switch have found those two clients to be useful, although Linkinus is shareware.