paranormal activity.... you can watch it for free at www.watchfreelinks.com the site looks a little sketch but dont let it fool you its legit i use it almost everyday.
last house on the left is really scary. it's really disturbing too, theres a pretty graphic rape scene involved and the ending is totally disgusting and twisted, but it's definitely scary!
if you're looking for less twisted and upsetting and more jumpy and in your face, i'd recommend a slasher movie like texas chainsaw massacre, wrong turn, or my bloody valentine