The Shining, a classic. My favorite horror movie is The Audition, or anything Takashi Miike makes for that matter. Although recently I did see the Thai version of Shutter which was pretty scary, I had chills when I saw the ending. (Don't confuse it with the shitty american version)
poltergeist has made me fear chairs and the dark.
and i think shutter and the ring and all those asian horror movies have made me scared of my own house.
"to the worm in horseradish, the world is horseradish."