I too like:
*The Shining (original- superb atmosphere, although I don't like how they took short cuts with the story.)
*The Ring (the horses on the boat were unsettling, very atmospheric).
*Psycho (classic and powerful).
*The Grudge (nice and creepy).
*28 Days/28 Weeks Later- both are good, the first is better if you like something with a "zombie feel" to it, but in this case they are not zombies.
Two movies that really gave me the creeps were:
*The Blob (remake- when they are at the hospital, the girl goes out to the lobby, the boy sits down to make a call. She comes back and he is covered with the blob stripping his flesh with an outstretched arm. She tries to pull him out but only succeeds in pulling his arm off.)
*The Fly (remake with Jeff & Geena- the ending just gave me a very unsettle feeling and it takes a lot to do that.) Even the ending of the original gave me an unsettled feeling but considering when it was made it's not nearly as horrific as the remake.
And I admit the original Exorcist was very unsettling. It's a movie I never need to see again.