If you like the Facebook type of chat and want something similar on your website, then this jQuery chat module is exactly what you are looking for. Though it lacks rosters, you can’t see which users are online, it is rather easy to implement.
How it effectively functions, I can’t say. I haven’t tested it (but the comments on the developer’s site are comportable).
It’s features include;
– Gmail style bottom right display of chat boxes
– Keeps chat boxes open and stores state (data) even when pages are browsed/refreshed similar to Facebook
– Displays “Sent at…” after 3 minutes of inactivity
– Displays “X says…” & blinks chat boxes when window is not in focus
– Minimize and close chat boxes
– Auto-resize of text input box
– Auto-scrolling of chat text
– Auto-back-off polling policy (hits the server less-often when chat activity is low)
– Extremely simple to integrate into existing site
It is compatible with all the popular browsers out there, from Firefox 2+ to Opera 9+, via Internet Explorer 6+ and Safari 2
Update 2: I’ve used this Facebook-like jQuery on a couple of projects and it works pretty well. Its compatible even with the most current version of Firefox, Chrome, Opera. Issues arise with Internet Explorer 8. For instruction on how to get this script on your website, hit the link below and follow the instructions.
jQuery Chat Module script is released under the GNU/GPL license for non-commercial purposes. For commercial purposes, buy a license.