I showed this Sundance Channel documentary to my students this morning. It covers the Milgram obedience experiments, the Stamford prison experiments, as well as some smaller experiments having to do with the Kitty Genovese stabbings. It discusses these frat boys who hazed someone to death and Abu Graib.
This program has excellent value in the class room. I've used it before to bring attention to the power of the situation and how dependent morality and character can be.
This was my third time watching it. I'm always sort of creeped out by the guy who was the ringleader of the guards in the prison setting.