I know Penn State uses a Pass/Fail system, including Honors, High Pass, and Low Pass (? I think). Which basically translates into letter grades but makes you feel better nonetheless. I can't remember the % point breakdowns but you can find it on their website somewhere. Hope this helps!
The University of Miami is P/F for the pre-clinical years, but if a professor gives you a numerical score in the course then that is also included on your transcripts. How this can be P/F is beyond me. The third year is not P/F (they give you only numerical scores), and the fourth year is strictly P/F (no numerical scores reported).
I don't know offhand which schools are pass/fail, but I'll second the suggestion to buy the Princeton Review Big Book on Medical Schools. It's got this information on every med school in the US and Canada.