Woo hoo movies!
The Fifth Element: This is my all-time favorite and I'm not sure I can put my finger on exactly why. To me it's just a perfect storm of fun sci fi escapism and impeccable art direction.
Mad Max 1 2 and 3: It has spawned countless imitations but Mad Max has yet to be beaten in the "awesome post-apocalyptic mayhem" genre.
Eternal Sunshine of the Spotless Mind: So far I have loved all of Michel Gondry's movies but this is still his best, and probably Jim Carrey's best movie too.
Back to the Future: These movies defined so much of my childhood it's not even funny. I remember as a kid every friend I had claimed to have a cousin who had a friend who owned a hoverboard. And I always believed them, because they HAD to exist, right?
Alien + Aliens: They've been mentioned a couple times already but these are both incredibly cool movies and they never get old.
Terminator 1 + 2: I have a special fondness for movies involving giant and/or killer robots, and the two Terminator movies that Cameron made are some of the best action movies of all time. Too bad the third one sucked.
Armies of Darkness: Bruce Campbell is legendary.
Jaws: C'mon, it's a classic! The principal actors all put in killer performances.
The Life Aquatic: Some people think this was one of Wes Anderson's weaker films but I love it; the bright colors, the stop-motion-animated creatures, the characters, everything about it.
Matchstick Men: Nicholas Cage is awesome. He is more awesome depending on how neurotic his character is, and how many times he just flips out at someone. In Matchstick Men he's completely insane, so mathematically speaking it is the best Nicholas Cage movie ever made.
Starship Troopers: All of Paul Verhoven's sci fi movies are awesome but Starship Troopers is probably my favorite. Nonstop ultra violent hilarity. I am still utterly perplexed as to how this movie managed to even get made.