My scariest was a Texas Chainsaw Massacre nightmare when i was 8. I was living in a haunted house (i have photographic proof, on a floppy disk somewhere)
I dreamed there was a crowd of people around a lightpost in a parking lot, and there was a nondescript building by said pole.
I went upstairs, and the 4th step up i heard a chainsaw, and i ran out being chased by Leatherface. I ran to the crowd, and tryed to jump in, but they kept pushing me out. I turned to be faced by Leatherface, he began a cutting motion toward me, and i woke up.
Oh, and i had a dream that bees were stinging the fuck out of ma brain. Freaked me out.