I don't think Saw is neccesairly (sp?) scary, it's just gross!
I think The Blair Witch Project is the scariest movie I ever saw. I'm getting goosebumps right now, as I write about it. Um... especially the end.. where the go into the basement and one of the guys is in the corner, and then the girl and her friend scream and drop the cameras. Also when they're in the tent and you can hear children laughing and the whole tent shaking. (And they're all alone in the forest.. actually video taping it, this is not really a movie, a documentary, since I believe they said it's real) You can't imagine how I felt. I didn't sleep for weeks, and I had to be alone at home every day, I stopped eating, and I was just so freaked out. To make it worse my friend (whom I had a huge crush on ) made it worse by putting that figure, person, stick thing near my bed.. This was about 2 years ago and I watched my first scary movie since then a week ago. I pissed my pants, literally, and I almost cried, I was shaking... my mother and I left before it ended.

Oh, and I think what added to my "phobia" is that I lived in a house that was haunted, after I saw that movie, I saw like a shadow person, heard people talking... One of the worst years of my life basiclly..
sorry, long post!