A really good book that came out last year is
Lunch Lessons, by Ann Cooper and Lisa Holmes. Besides talking about what we can do to improve the food our children eat at school, it has lots of kid-tested recipes.
Disclaimer: I worked on this book. But I'm not the only one who thinks it's good: it just won the award for Best Book of 2006 on Health and Special Diet from the International Association of Culinary Professionals.