This one is on a personal note. We are in the process of putting together an exciting Twitter add-on called GuerrillaTweets and are looking for beta testers. 

GuerillaTweets is a powerful mobile marketing solution that extends Twitter by making Tweets accessible via SMS. With GuerillaTweets, you can promote your products, services, or events to more people by making your posts instantly available to anyone with a cell phone. No Twitter subscriptions or smartphones required - just a simple text code and easy-to-remember keyword is all they need to get your latest update, anytime, anywhere.