That ending is a shock, eh? I was watching and when it dawned on me, it was like "what the...".
Anyway, haven't read the whole thread and not sure your original criteria, but here is a list of great movies that you should eventually get to...
Dr. Z
A Clockwork Orange
Raging Bull
Fargo (someone mentioned this and it is a great movie, w/Clay Buchholz lookalike).
The Deer Hunter
12 Angry Men
Easy Rider (cult 60's classic)
It's Beautiful Life
Citizen Kane
Sling Blade
Dr Strangelove
American History X
American Beauty
Lawrence of Arabia
Once Upon a Time in America
Cool Hand Luke