I'm not much of a fan personally of "spooky" books but many teens really enjoy them. Unsophisticated readers often enjoy the Goosebump series. I have been wanting to read Coraline by Neil Gaiman because Neil Gaiman is such a huge name in YA lit (he is often mentioned by other writers as being an inspiration). Coraline is a short book and I read it in an afternoon. It IS creepy with the "other mother" and the parallel world she has created. That hand thing at the end probably has resulted in a few nightmares... And those button eyes...

Then there are the vampire books. I like Stephanie Meyers' highly popular Twilight series - but they are really more like romance or suspense than of the horror genre. Klause's Silver Kiss was good too. Am now reading Peeps by Scott Westerfeld. His books are popular with the teens in my family- they refer to them as urban fantasy. I love his Uglies, Pretties, Specials series (broke my rule about only reading one book in the series). But this one - I don't know.