The Dark Knight: 9 out of 10.
I'm only a year late on this one. It could be worse. I still haven't seen Doctor Zhivago, and that came out before the Leafs last won the cup.
Allow me to report stuff you've probably read a thousand times before. Heath Ledger is fantastic as The Joker. He's damn good, and you're mesmerized whenever he speaks. Even if he had lived, I'd have rooted for him to win the Oscar, that's how good he was.
The movie itself is probably the best comic book movie ever made. It's dark and thought provoking, telling an interesting story with great acting and special effects. It's just cool to look at, and there's an actual story there that blows away most comic book flicks.
I liked The Dark Knight. I liked it very much.