Muffins - make them with whole wheat flour, applesauce instead of oil, reduce the sugar, add in fruits and grated veges (zuchini, carrot, beets, etc)
Beans - black beans with taco seasoning... add cheese and serve or wrap in a tortilla
pasta - use whole wheat noodles and add veges to the sauce (shreaded carrot, finely chopped spinach, chopped kale, etc)
stir fry - tofu is a huge hit around here
pad thai - ds LOVE pad thai. you can get tofu or chicken in there along with egg.
sub soy or turkey hotdogs when you serve them
veggie burgers!
mexican rice, fried rice, etc (use brown rice!)
yogurt with granola
make chili with lots of beans and pack that in one container. Put another container of elbow macaroni (whole wheat!) and a small serving of cheese... they can mix it all up at lunch for chili mac!
mini-pizzas - use whole wheat english muffins and add tomato paste, mozz cheese and veggies
Also, I see a lot of responses about the fact that kids are drinking a lot of milk and not eating much. This is really a bad idea. Too much milk inhibits iron absorbtion and if they aren't eating iron rich foods to begin with then you will have a problem on your hands. Often kids who drink too much milk won't eat other things because the milk makes them feel full!