I've just finished my first Twitter app. It's basically a just a about using OAuth to allow people to sign up to KungFuPeople.com without having to pick yet another password.
I simply took the oauth.py module by Leah Culver and wrapped it with some useful functions taken from a similar Twitter app we've done at work.
Unlike other Twitter apps for this one I'm using Twitter solely for handling authorization and authentication. That means that it has to work with the existing user + profile functionality but just side-step the sign up and login.
Next goal: Google OAuth