How to pack the perfect punch for back to school lunch

As the new school year gets off to a start, many of us are back to the endless round of packed lunches, coping with different tastes and working within the confines of healthy eating and anti-allergy policies in school.
The question is how to make lunchtime more exciting for the school kids in our lives whilst adding variety and interest, keeping food fresh and avoiding those lunchboxes coming back full at the end of the school day?