Also liked The Ring (first one, the sequel sucked), and The Descent. Frailty was also a good one, though not sure I'd call it a "horror" movie. Others I've like include Creepshow, Scream, Alien, An American Werewolf in London and Angel Heart. I've heard that Henry: Portrait of a Serial Killer, is about as disturbing as it gets. I doubt I'll ever watch that one.