Not got into Twitter yet? This book might tempt you. Here's how it is described:
"This practical guide will teach you everything you need to know to quickly become a Twitter power user, including strategies and tactics for using Twitter's 140-character messages as a serious--and effective--way to boost your business. Co-written by Tim O'Reilly and Sarah Milstein, widely followed and highly respected Twitterers, the practical information in The Twitter Book is presented in a fun, full-color format that's packed with helpful examples and clear explanations."
Here's a sneak preview on Slideshare: