Counting by 7s, by Holly Goldberg Sloan

Willow, twelve year-old genius and oddball, copes with the world by counting in sevens.  But no knowledge or coping skill can prepare her for the death of her foster parents.  Instead, she finds that life's salvation comes from the most unexpected places:  a Vietnamese family, a dysfunctional guidance counselor, and a Mexican taxi cab driver.  And, in the same odd way that they have managed to help her, she ends up changing their life in equally unexpected ways.

The general path of the story won't surprise anyone -- it basically begs to becomes a tale of random good fortune and luck -- but what makes this book a joy is the connectedness of the random events.  The message is that no matter how hard you try to order the world and control the outcome, in the end you never quite know where you will end up.  Meanwhile, it is such a nicely written book with such charmingly odd and unusual characters, that you'll be willing to swallow a whole lot of sentimentality along the way.  As with many books of this sort, it's more designed for adults (and librarians) than for kids, but one hopes that children will just enjoy a gentle story.