Stephen King's basically the only person who ever managed to write something I find remotely scary. If you're 'scared shitless' then likely your attention span will double. If not, and all you want is a 250 page book, what you're getting will likely be cheap shocks. Carrie, Salem's Lot, The Shinning, etc, are as far as I can help you.

At the Mountains of Madness is a good short read. If you wanted to read some older stuff Washington Irving's stories are really nice.

There's also the Haunting of Hill House.

Joe Hill's Heart Shaped Box... Good creepy little read.

There's always the classic I am Legend by Richard Matheson, The Revelation by Bentley Little, if you're into science fiction and want something dark and grab you by the throat by a writer who CAN kick your ass, try reading anything by Peter Watts. Most all of his stuff is free on his website through a Creative Commons license. Just go to rifters.com He has novels, short stories, etc.

I'd agree with those recommending King for a first horror read. I think he's one of the more accessible horror authors. I know people that read King but really don't read anything else in the horror genre. I'd pick one of his short story collections. I really liked Night Shift.

I honestly think King is a little to heavy for an introduction to horror....wait the first horror novel i read was The Tommyknockers.....never mind

jack ketchum books are qute short and easy read, but like u said u read off spring, try girl next door.

or this is a very good read

living dead girl
http://www.amazon.com/Living-Dead-Gi.../dp/1416960597