Your Biggest Fan or The Panic Room by me. They're both part of a series but can be read as standalones. They're kind of disjointed. Like, you can read any of them as standalones but the concept is a series, even though it doesn't show any connection to either of them. :p
I have a few, but I'm only just starting out in the horror genre =] Perhaps you could give me some tips ^_^
Anyway, I have two one-shots, Mariya and Come With Me. The first is very different to anything I've written before and the second one seems to hit a nerve with everyone who reads it xD It even scared me while I was writing it.
I also have a three-shot, Hellingly, which takes place in a real abandoned mental asylum and has a really unnerving, creepy twist in it.
Hope that's something like what you're looking for =D