I've been playing with Samir Ghobril's new contacts app, Mingle (website)(iTunes). The application breaks the usual "tap to view" paradigm of a contacts app. Instead, you swipe a contact and it gives you several options, including email, Twitter, call, and chat. This is not unlike some of the email applications that give you multiple options when you swipe an email message. I still find it fascinating how developers are innovating some very traditional categories of software (like contact managers) now that we've got these new interfaces. Mingle is definitely worth checking out.