Spaghetti Book Club
Book Reviews For Kids by Kids!
http://www.spaghettibookclub.org/

Kids Reads
Join a bookclub or find out about cool new books for kids!
http://www.kidsreads.com/

KidLit
More Book Reviews For Kids by Kids
(Warning: many of these titles are suitable for middle and high school kids only)
http://mgfx.com/KIDLIT/kids/artlit/reviews/index.htm

Building Rainbows
Read and share book reviews with other kids
http://www.buildingrainbows.com/

Just for Kids who love Books
Kids write in to Alan Brown about their favorite books and he posts what they say on his site.
http://www.alanbrown.com/

The Reading Corner
Check out award winning books selected by respected librarians. Includes lists of State Book award winners!
http://www.carr.org/read/

Kids Bookshelf Reviews
Choose to search by author, illustrator, title and age
http://www.kidsbookshelf.com/review.asp