This application is a complete rewrite of the YakAlike extension, so it would be arrogant for me to not acknowledge the idea that Adam Wisniewsk came up with. So, Adam, thanks for a genius idea -- please contact me so we can collaborate on the next version.

Now quickly, let me thank the people behind, Mozilla Firefox, Gentoo, UnrealIRCD, CGIIRC, Apache 2, PHP, nano, VIM, Perl, Fluxbox, OSWD, and many more. This extension was written with/requires all of those things, and many more, but that's what I came up with.
This is basically a firefox extension that lets you chat with people who are visiting the same sites that you are in your firefox browser. Now I'd love to see you try that with Internet Explorer!

Download: Quickchat for Firefox

Source: Quickchat Homepage

Another digg find.