best of 2008
Following diceytillerman, I'm listing my best books of 2008. All of these are middle grade or young adult. I've marked them with an asterisk (*) if they are sequels or parts of series. And I've read almost nothing this year I didn't review, so there's so much here that's missed, I'm sure!

Fantasy and science fiction:
Little Brother by Cory Doctorow
House of Many Ways* by Diana Wynne Jones
Graceling by Kristin Cashore
Flora's Dare* by Ysabeay Wilce
The Hunger Games by Suzanne Collins

Realism:
Return to Sender by Julia Alvarez
This Full House* by Virginia Euwer Wolff
The Porcupine Year* by Louise Erdrich
Antsy Does Time* by Neal Shusterman

Books that weren't as good as I wanted them to be but were still very enjoyable:
Princess Ben by Catherine Gilbert Murdock: very enjoyable but the well-meaning attempts to deal with body image politics backfired badly.
Rex Zero, King of Nothing* by Tim Wynne-Jones: excellent, like everything he writes. But the Rex Zero books are too nostalgic for my tastes.
Impossible by Nancy Werlin: this book was beautiful, but one of the things I like about Nancy Werlin is how grim she is willing to be. This story tied up all the loose ends more neatly than I wanted it to.
Cycler by Lauren McLaughlin: I really wanted to love this book with its protagonist who unwillingly gender swaps monthly. I got hung up on some really icky race politics that are a tiny part of the book, so it's hard for me to judge the text fairly aside from that.

Books that were way better than I expected them to be
Mousetraps by Pat Schmatz: this looked like a really fun, silly book with a pat message about accepting your gay friends, until it got unexpectedly dark.
Zoe's Tale by John Scalzi: Scalzi decided to write a standalone young adult novel that takes place in the middle of an existing adult science fiction series. It sounded like a train wreck to me -- but the book was great, and worked very well as a standalone. He didn't give me any interest in reading the adult books in the same series, but it did make me want to read more about Zoe from her own point of view.