What do you use for IM? Yahoo Messenger? MSN Messenger? Google GTalk? AIM? IRC? Gadu-gadu? Stay in touch with all you IM buddies only with using one IM: Pidgin. This is a simple-to-use yet flexible IM client.
Pidgin supports a whole host of protocols and as long as you know what protocol to choose and your username and password you can be online and chatting in seconds. Pidgin also allows you to make use of more than one IM account at the same time - handy of you have multiple IM accounts.