Perhaps I should add a new category for web messengers itself. A new Web messenger is created almost every month and even better than the previous . RadiusIM is the new kid on block. RadiusIM supports Yahoo!, MSN and Gtalk Id’s on their completely ajax based web service.
The site has a good UI and responds nicely so far. Again … It will be great alternative for the people who have blocked meebo or e-messsenger in their office or school ;) .