I have been strongly recommended hosted.im services by a friend. Basically, just like you can use Google Apps to externalize your email maintenance, they do the same for chatting, and you keep using your domain name after some basic DNS setup.
Some will say google does the same – they sure do, but Google only integrate with AIM and Jabber nicknames, while hosted.im support ICQ, Yahoo and Hotmail. Much better !
You just have to set up some basic DNS entries – a 5 minutes job.