People often discount literature in terms of horror value, but some books can really get to me in a way that film and video games have not yet. Short stories like I have No Mouth and I Must Scream are absolutely incredible at delivering short bursts of creepiness, as are a number of Neil Gaiman's short stories. In addition one I found to be kind of horrific and definitely very strange is The House of Leaves, which has inspired so many story ideas of mine.