Twitter is service that combines instant messaging, SMS, social networking into one little package that allows you to keep the world apprised of your every movement (you wouldn't want to deprive the world of this, would you). It also allows you to keep track of your friends, so connecting with your friends on Friday night gets easier.

If you want to get started with Twitter, or you just want to find out more about this service, this site offers the best newbie guide to Twitter out there.