Yoono- Social networking and IM friends all-in-one | Firefox Addon
Yoono is an easy to use sidebar for your browser that allows you to connect to all your social networks and instant messaging services - in one place. Get all your friend updates, update your own status, and easily share stuff with your friends.
I must say this is one of the coolest Firefox add-ons i have ever used . Why bother opening several tabs for Social network sites and several windows of Messengers , Yoono houses it all in one place.