oh ya lock stock is awsomely funny. guy ritchie did an aswome job on that 1Lock, Stock, and Two Smoking Barrels ..since Snatch was mentioned, which is a great movie, but I think Lock Stock is better.
Also, I've got to echo the Christopher Nolan goodness like Batman Begins/Dark Knight/The Prestige. I liked Memento a lot too.
In the Valley of Elah was a pretty good mindfuck of a movie, I thought. It's pretty damn depressing, though. I remember when we rented it a couple of months ago; four 23 year-old guys were having a hard time keeping it together during one scene in particular. It's not necessarily a movie I think is really, really good, but it was one that stuck in my head for the next few nights.
And some of my random favorites..
There Will Be Blood