Some of my favorite Halloween Movies (aside from those on Melissa's list) include:
Sleepy Hollow: A rock-on Tim Burton movie...so you know it's visually stunning. With Johnny Depp and Christina Ricci. Awesome!
The Lost Boys: A very 80's vampire movie. Yeah, it has the two Coreys in it. And it's still one of my favorites. Quirky.
Ginger Snaps: Lycanthropy as a metaphor for menses? Yep. And it works, really. (Okay, maybe it's a little heavy-handed, but I think they pull it off!) Mimi Rogers as the hair-scrunchie-and-crafty-applique-sweatshirt-wearing mom is hilarious.
Scream I, II, III: All fantastic. I love the combination of humor and horror.
Saw I, II , III : Yeah, the first one is the best. Without a doubt.
Frailty: Very creepy.