Jeff Miller put together a list of "Twitter Users Most Followed by Readers of Hacker News":<p><a href="http://jeffmiller.github.com/2010/07/28/twitter-users-most-followed-by-readers-of-hacker-news" rel="nofollow">http://jeffmiller.github.com/2010/07/28/twitter-users-most-f...</a>
My advice is to do searches of your interested... Find people who talk about what you care about; even more importantly, people who interact with their followers. It all depends on what you care about.
Felicia Day (@feliciaday). She's a celebrity whose life is nothing like mine, and yet her tweets are the most sincere and down-to-earth of nearly anyone I follow. Her tweets put things in perspective.