My favorite horror movie of all time is The Sixth Sense. It's extremely well done and still has the most shocking surprise ending. The movie is over eight years old now. Yet I still consider it a great sin to reveal the secret of this movie to anyone who hasn't seen it yet.
Jason vs. Freddie is another good one. You don't need to be familiar with either series to follow this movie since a background is provided for each one. Their backgrounds and vulnerabilities play into each other very well and make perfect sense.
The Evil Dead is the one movie that scared me so much, I had to turn it off because I was getting so short of breath. I still have yet to see the whole thing. Perhaps I'll need a tranquilizer and an oxygen mask to make it though this one
I just saw Invasion which is sort of a pseudo-remake of Invasion of the Body Snatchers. That was terrifying and extremely well done. Kidman does a great job in this role playing someone who has to hide her emotion, yet you can still see the emotions. There was one bit of comic relief where in the background, the TV news was talking about how President Bush and President of Iraq Al Sadr made a peace agreement. My friend and I did a double take and then cracked up laughing. Actually, come to think of it, that was the scariest part of the movie