Fight Club - I can't stress enough the greatness that is this movie. See it multiple times. The first time you're going to be thinking "Jeez. That was weird." It takes repeated viewings to achieve the full effect though. So many great moments.
Memento - It was mentioned before, but it needs another mention. A movie made backwards. When you see it, you'll know what I mean. It's very good.
Bubba Ho-tep - Bruce Campbell as Elvis in a retirement home who is fighting a mummy who threatens to suck everyone's soul out through their arseholes? His sidekick is a black guy who claims to be JFK? It's as awesome as it sounds.
Goodfellas - I liked this crime drama better than the Godfather. Maybe I'm weird, but I doubt I'm alone.
The Big Lebowski - That rug really tied the room together.