I get goosebumps (even though I've seen the movie MANY times) when they get/watch the videos from the steps. To me, that's one of the scariest scenes in a movie, period.
From when I was probably way too young to being seeing it, The Omen with Gregory Peck and Lee Remick, but it is an anguished kind of fear because of those two incredible actors...
And as a teen, Jacob's Ladder, although I have blocked all memory of the story.
As an adult, I was completely scared to death by The Ring, really surprised, too. I love that movie.
I was living w/ my sister and she was out of town for the weekend so I decided to watch THE BLAIR WITCH PROJECT. I had heard about it but wasn't sure what it was about. So I stroll on down to the video store and pick it up. Put it in the dvd player and think "Oh good, a documentary". Well, you can all see how scary that movie would be if one was to think it was a real doc. I was almost crying, sitting in our apt. alone for the weekend. I called a friend and she calmed me down and informed me it was a spoof.
I'm afraid I'm the worlds biggest chicken since doesn't take much to scare me at all, but the scariest movie I ever saw was The Ring. I actually rented it on video when it came out at the video store which was so stupid in and of itself, but then one of my friends called me while I was watching it and then hung up (bad cell phone connection I later found out). And I'm already all spooked by that freaky girl coming out of the TV to kill people so what I heard on the phone was (I'm not kidding here) "seven days ..." . Scared the living shit out of me! I seriously couldn't sleep for like a week or something. Argh!