Some that come to mind:
- I watched "Ex Drummer" a while back, which was sick (sick as in twisted, not as in awesome), but funny in a very disturbed way (ever seen a movie in which everyone is a twisted asshole without redeeming qualities?). I wouldn't rank it among my favorites to be honest, just mentioning it since I saw it recently.
- "Shichinin no Samurai" is a classic, and for good reason. It's not too much of a stretch to say that every modern action movie owes a little something to this one.
- As people have said before, "Der Untergang" is awesome. Humanizing a globally hated figure like Hitler without making his actions look any better than they were is an impressive feat.
- Also mentioned before is Ingmar Bergman, the most famous of his movies being "Det Sjunde Inseglet". If you can stand the rather slow pace (it's no action movie), you have no excuse not to see this one.
- "La Vita e Bella" is just amazing. A lot of emotion in what seems like a very light-hearted (some say too light-hearted) movie at first glance.
- "Oldboy" is awesome. You have to see this one to know just how awesome. Really.
- The "Mou Gaan Dou" trilogy, better known as "Infernal Affairs" (or "The Departed") to most, is just so much better than the English-language ripoff remake in every possible way (if you don't mind subtitles).
- "John Rabe" was very impressive. Think "Shindler's List," but set in China.