Meebo & Mabber
Meebo is an Ajax instant messaging client that works with major instant messaging services. Its website allows you to log onto AOL, ICQ, Yahoo! Messenger, MSN Messenger, Jabber and Google Talk so that you don’t have to worry about having the software application if you are away from your main computer.
Mabber is another web-based instant messaging client similar to Meebo integrates ICQ, MSN, AIM, Yahoo and Jabber in one client. You can also download their Mobile client to use their service from your Mobile phone.