Well Im 16, but I still think people my age should read like classics, especially things like Pride and Prejudice, and Jane Eyre. Um, what else? I would recommend Kommandant's Girl and The Diplomat's Wife. Also I just started to read The Time Traveler's wife, and my best friend said it was amazing. There is also My Sister's Keeper, im not sure if you would say that is a "teen" book or not? My mum wants me to read To Kill A Mockingbird, so that too lol.

I think some chick lit (the non-explicit kind) is appropriate for teens. I read Confessions of a Shopaholic, and I think teens would enjoy that.

I think that several teens are at a reading level that they can read most books categorized as "adult literature." I mean, they read several adult books in their English class (like "God of Small Things").

I'm 17, and I really enjoy what are classified as "classics",
I also find that a lot of adult fantasy/science fiction is very interesting; and good for teens, such as Cecilia Dart-Thornton or Raymond E. Feist

Anything by James Patterson, especially the Maximum Ride series, although at Borders his books are stored in the junior section and the adult section. These are really good books that are fast paced and interesting the whole way through.