Snow Day: I never had snow days as a kid (I grew up in Florida), but this film totally captures the essence of what that experience must be like. A great kids movie, but one that I honestly enjoy (free of irony) to this day. Look for an early appearance from super hottie Emmanuelle Chriqui.
Gladiator: Russell Crowe stormed into the action hero's handbook in Ridley Scott's sword-and-sandal epic. Winner of Best Picture at the Academy Awards, this one will most likely be on everyone else's list: but that's for good reason.
Memento: The world's introduction to Christopher Nolan (aside from the little-seen Following), this masterpiece of cinema is a mindbending story expertly told. A sign of the great things to come from one of the most talented directors working today. Guy Pearce was fantastic, and the cinematography is so good it looks as if it were shot yesterday.
American Psycho: Mary Harron's ultra-sharp satire of 1980's culture went over my head the first time I saw it, but has since become one of my favorite flicks. The ambiguous ending (was it all in his head? Or did he actually do those things?), the business card scene, Huey Lewis, kittens and ATM machines - hilarious comedy and disturbing violence collide to impressive results.
Remember the Titans: This wasn't the first great sports movie, but I don't think one has topped it in the years since its release. The subject matter wasn't new, the genre archetype wasn't new, but this movie accomplished its goal with style, class, emotion, flair, and fun.
X-Men: Inspired casting and the novelty of seeing some of my favorite cartoon heroes on the big screen overshadowed a too-small budget and some slow pacing here. This movie wasn't the first comic book film by a long shot, but it started off this decade with a bang and its success laid the groundwork for everything that came after. I'm still pissed Cyclops was shafted in this series, though.
Mission: Impossible II: I wrote a review of this over at The Solar Sentinel a couple years ago, and while I don't agree now with everything I wrote then, this movie still rocks. I've become very fond of MI:III in recent years, but I still think this one has the edge over it. Visit that review, watch the motorcycle chase scene at the bottom, and tell me that isn't awesome. Plus, it's John Freaking Woo.