Coraline by Neil Gaiman is one of the coolest, scariest children's books out there. Sadly I didn't read it until last year, but it perfectly captures the thoughts of a 8-10 year old girl. Coraline was made into a graphic novel as well as a movie, and each incarnation of the story is beautiful and scary in it's own way.
This is the book, which in and of itself is beautiful enough.
The copy of the book that I own has amazing pictures by Dave McKean.
There is also a graphic novel, which has spooky pictures, but in the end is considerably less scary then the book.
And of course, there is the movie Coraline, which came out in March. It's stop-motion and gorgeous. The story was fleshed out a lot for the movie, but the extra plot was added seamlessly.
And then there is... fanart! Come on, you saw this coming. Emmy C did a beautiful drawing of movie!Coraline. (click to see it nice and big.)
And here is another random, completely adorable Coraline and Wybie I found on DeviantArt!! (rachelo)
So go read/watch/thoroughly enjoy Coraline in all it's incarnations!