Paranormal Activity wasn't a "Hollywood Movie", a guy made it in his house. Hollywood was gonna remake it, but they decided not to. The movie scared the shit out of me. I hate the claustrophobic restricted feeling of watching a film within a film like Blair Witch Project, it creeps me out. Also I was probably too young when I saw the scariest movie of all time, The Exorcist, so demon movies get me.
The part where she is standing over him in bed while the clock goes by for hours was one of the scariest things I've ever seen. I was dreading her doing something and I sure didn't want her to turn towards the camera. When I saw the movie, at least 20 people left after that scene, and they weren't bored, they were running for their lives.
Never saw Drag me to Hell, but the remake of the Ring was another classic.