Have you seen Jay Rosenblatt's "Human Remains":http://mubi.com/films/23808? It's subtitle is "A film about the banality of evil."
Excellent suggestion. Added. (I hadn't seen the Alan Clarke version until the DC).
I think Alan Clarke's version of "Elephant" would probably fit in better than the one by Gus van Sant.
It'd be typical to even speak of Pasolini's final work to a list like this, so I won't, because I'm not feeling rather qualified as I've only seen about four of the twenty-two films on this list.