“What are you doing?” Twitter is a micro-blogging social networking site that asks that one question, and gives you 140 characters to broadcast an answer to all your friends, family and co-workers. Intrigued by the possibilities? Here are a few guides to get you started: MasterNewMedia’s Twitter – A Beginner’s Guide , Caroline Middlebrook’s Big Juicy Twitter Guide, and Rafe Needlemen’s Newbie’s Guide to Twitter.