Meebo.com - Instant Messaging Everywhere

Meebo.com is a browser base instant messenger client that allows you to connect to AIM, Yahoo!, MSN, Google Talk, ICQ, and Jabber. This site is great when you are on a computer that you can't download or install software on or if your workplace monitors your instant messaging. It uses your current buddy lists and username. It even lets you sign on invisible, so you can chose who knows you're online.