Trick 'r Treat (2007)

This movie renews my faith in modern American horror (something that needs periodic renewal). It may not be the scariest movie you've ever seen, but it's clever, it's original, and it's just an all-around enjoyable movie. My only regret is not holding off on this one until Halloween; it would definitely put you in the spirit. I'll probably re-watch on Halloween anyway, that's how much I enjoyed it. I should also note that I am a total sucker for anthology movies (Creepshow, Cat's Eye, etc), so that fact that this has four interwoven stories gets extra points from me.