Helter, Skelter - when I read it in HS. Sscared the bejeebus out of me, so I finally realized I could not read it before going to bed! Re-read it last year, and I was fine, although while it didn't give me nightmares, it gave me very strange dreams...
Remember how I say I live near Death Valley? Dad can't help but point out the history of the song every time he plays the White Album. I've kind of grown to ignore it at this point. Never read a book about it, though.
My dad kind of desensitized me to this, Edgar Allen Poe, and Lovecraft's works.
General scary, there's an entire topic on eHell, and there's a forum called Paranormal Soup. The latter is reports of stories from personal experiences, and most of them tend to be true. My favorite from the board was a story of a nightshift worker doing guard duty at a building. He heard the alarm trip, went to check it out himself, and saw a very ghostly man in an older looking guard's uniform, pacing the scene. The ghost turned around, saw the corporeal guard, and charged him, looking to be screaming, because he was guarding his property! If I remember right, the ghost dissolved as he charged and kind of sunk into the ground. That scared me good for weeks!
(If I could find the link for that story, I'll share it.)
There also exists a true anomaly called Number Stations, and Oddity Stations. They are spy stations, but sometimes, the recordings themselves are enough to freak someone out. Like Swedish Rhapsody. http://www.swldxer.co.uk/swedrhap.mp3
Taken from this page:http://www.simonmason.karoo.net/page13.html
There's also Papa November:http://www.swldxer.co.uk/pnjun84.wma
Yes, I enjoy tracking these... we only get V2a on any regularity, though. That, and PN and Swedish Rhapsody have been off the air for a few years. Papa November much longer, though.
I enjoy real life creepies the most, so I hope no one minds my suggestions. The best kind of unknowns are the real ones!