iChat is more capable that you might think. Small Dog uses iChat’s Jabber functionality for our own internal instant message system. It’s a great, secure solution for us, and we’ve used it for years.
You might not realize that the chat functions in Facebook can be used in iChat, eliminating the need to log in to the ever-changing website. Just go to your Facebook account settings and retrieve your username, then fire up iChat.
In the iChat menu, select Preferences and make a new account. The account type is Jabber. Your username will be < youruser >@chat.facebook.com with the usual Facebook password. Click on the disclosure triangle to show server options, and enter chat.facebook.com as the server name. The port to use is 5222.
iChat also support Google Talk and, of course, AIM (AOL Instant Messenger).