I had been using Trillian to IM all my friends from ICQ, AIM, MSN, Yahoo, and gTalk; however, I switched to the web-based Meebo.com awhile back. Anyways, after being a little frustrated with the feature-lacking Facebook chat feature I just discovered that they added Facebook support to Meebo!
It’s very basic as well, but you can see a list of FB online friends and determine at a glance when they come off from being idle. The input area is nicer as well and each post shows a time which is nice. Check it out. Meebo is a free service.