What are so really good books (no series) for ages 11-13?

Question:

What are so really good books (no series) for ages 11-13?

I'm looking for a book (NO SERIES) for my friend's 12 year old daughter (its her birthday and she wants some really good books THAT ARNT SERIES). It can be ages 11-13. I will pick the most thought and researched through answer. Thanks so much guys!! :D

Best Answer - Chosen by Asker: I recently gifted Princess Academy, by Shannon Hale in a similar situation, and the girl I gave it to absolutely loved it.

I've read this book myself, and it has become, by far, one of my favorite young-adult books. Plus, that's not just my opinion--Princess Academy even won a newberry award. I would try to give a brief plot synopsis, but anything I say won't even begin to fathom how delicious this story was.
(And yes--it was even a stand-alone!)

So, with that said, I'll just post the link to Shannon Hale's site, where you can read a little more about Princess Academy.

Happy reading!