Wanting to be Her is an absolutely amazing book. I think I've mentioned it before, but it's worth saying again. The book is directed at college aged females, but I think it would be beneficial for even young teens.
It talks about liking who you are without focusing on your body image alone. Michelle Graham provides reasons to like yourself for who you are - with a biblical basis for much of the information.
Unfortunately I lent out my copy to a friend and never got it back. Or else I'd write a lot more.