I think it really depends on when you saw the movie. Although I've seen a lot of good horror movies as an adult, I don't really consider them scary. Paranormal Activity, for example, I found extremely boring. Perhaps had I seen it as a child I would have found it scary. As far as movies that scared me as a child, I'd have to say The Exorcist, The Shining, and A Nightmare on Elm Street were the scariest back then. Some of the best horror movies I've seen in recent years include Drag Me to Hell, Let Me In, Ringu, and [REC].