One of our constant questions at ACP Internist is: What is Twitter really useful for? Everyone has a feed but no one is really saying anything. Just as we'd given up on a practical purpose for it, (surgery aside) we found two bread-and-butter applications for internal medicine: smoking cessation and weight loss.
Qwitter helps users track how many cigarettes they smoke, keep a journal, view progress over time and share info with supporters.
Next, you can Tweet what you Eat, using Twitter to set up a diary, track consumption, enter calories and find our how many are in the food you eat.
Personally, I think Twittering would help reduce smoking or eating just because it's something else to do with your hands. If you try these, or let patients try them, let us know how you fare.