I think my top six are... hmm... in no particular order...
Donnie Darko, The Village, Signs, LWW (of course), Dirty Pretty Things, Howl's Moving Castle. And then maybe I'd have to say Red Eye, which while it was quite generic managed to keep me really hooked; Mean Girls (omg, no perfection akin to that has ever been achieved on film again); Some Like It Hot; Roman Holiday; hmm... oh, and, of course... Teaching Mrs. Tingle, which for some reason I like watching more than anything else on Earth. It's so cool! And finally, The Ring (American version) was really, really, good but I wouldn't ever want to be in a state of such petrifying fear of really normal things for another seven days of my life... Oh, and (hmm, this is getting a bit long) Paradise Now was wonderful and really really powerful, not a light watch!
And then, of course, while it's not a film... Buffy the Vampire Slayer. What more can I say?