Darkness Falls didn't do it for me, was easily the worst acting and horror genre script I've seen in years. Blair Witch creeped me out, but I was more just impressed with the innovative style.
Anyway, the movie that still freaks me out is Poltergeist. I've had a few of those odd "I
KNOW that wasn't there a second ago" moments and I get flashes of that movie and will get a chill up my spine. But the real fugga was the Clown, man.. I can't look at a clown anymore. I saw this movie when I was like 9, and I saw clowns leaping out of dark doorways until I was fifteen.. My parents in their infinite wisdom even made me watch the clown scenes over and over to try and show me the "strings" on the clown..
I nearly pissed my pants when I saw Pee-Wee's Big Adventure a few years later.. when his bike was stolen, and the clown got evil.. nm, we've reached the TMI point