Something I just noticed is that there's a "medical" category now in the app store. Any doctors in the house? While we're at it, if there are, what's your favorite or most useful "medical" app? What about, for everyone else, your favorite health-related app? I'm quite fond of RunKeeper.
Most of the apps are appropriate for residents, medical students, others in training, and non-medical users interested in easy access to limited medical information. As a neuroradiologist, the only thing I have found useful, although not necessary is OsirX.