Although I despise the term "tween", I'm digging this blog that suggests books for middle school kids... I'd heard of very few of them...
If you have more time, this blog compiles nominations of books from children's book bloggers, and then gives out awards in many catgories (the cybils).
And this link connects to the Maine Book Award site -- I believe they are taking recommendations for 2010 now.
Finally, for us grown-ups, the Maine Festival of the Book is coming up soon -- April 9 -11th.