I'm trying to prepare for the US Physic Olympiad competition, what are some good resources?

I sucked at it years ago when I took it but a couple of my friends made the camp and one got a silver medal at the IPhO. Neither of them really prepared for the test. However, both had a solid grounding in mechanics and E&M at the level of a first year undergrad from a top university (think Princeton or MIT). Now they were lucky because they were able to take these courses at a local university during their junior and senior years. So my suggestion would be to read the two clic texts on these subjects: Kleppner and Kolenkow for mech. and Purcell for E&M. Also consider the Feynman lectures which present physical concepts in a very enlightening and intuitive manner.