TweetDeck is the best desktop application for Twitter. It's interface is very pleasing and organizes your "Replies" and "Friends" in a column format. The ability to create certain groups and to post directly to Facebook makes this the tool of choice for Twitter. Interestingly enough, TweetDeck has introduced an iphone version. Now for all the users who need another reason why they should switch to an Iphone, this is one main reason you should. If you are a social maven, then download it on the iphone and enjoy!