gomeals.com has the Go Meals HD App It is a great app to track food and diet and create awareness of eating habits. They have an app for the iPhone, iPad and Android devices.
fooducate.com Has a great app that allows kids to scan the food bar code and gives it a grade. It was awarded the Appstore 2011 best of the iPhone Health & Fitness category. Download it here
Diary Ping Allows you to find out where your milk comes from. It's great teaching students that milk does not come from a bottle, and finding out if it is locally produced.
Lose It! is a simple app with the concept of calories in and calories out. It combines nutrition and exercise.