Also, following up on Jaron's mention of German film Das Experiment. I was lucky enough to see it during the SF German Film festival at the Castro Theater about 8 months ago. While not a documentary by any stretch of the imagination (in fact, Philip G. Zimbardo who led the original Stanford Prison Experiment was in attendance and available for Q&A after the movie, and vehemently attacked the movie for it's sensationalist portrayal of his experiment), it's a real nail-biting thriller if you like that sort of thing. Worth 2 hours of your life.