BoardsConsult/RotationTracker
A while ago, I teamed up with an M.D./Ph.D. friend of mine and wrote a web site called BoardsConsult to help medical residents prepare for the U.S. Medical Licensing Exam, and a related site called RotationTracker to help medical schools evaluate and track the progress of the residents in their programs.
Although the sites are up and running and populated with a small but high-quality set of review questions, they are not yet open to the public.
If you have an invitation code, you can visit BoardsConsult.com or RotationTracker.com.