Foil packs - hamburger, chicken, sausage, turkey, whatever with onion slices, peppers, mushrooms, potato slices (whatever you like) and sauce (BBQ, Teriyaki, whatever) all wrapped up in foil and placed on the grill. Put fastest cooking items on top as you make your creation. When done eat right out of the foil, minimal prep, minimal mess, maximum enjoyment since everyone build what they like best in their foil pack.
Personal pizza - English muffin half, ladle on some pizza sauce, cheese and whatever other topping you like. Place in cooking pan or pie tin and cover with foil and place on grill.
Dutch oven recipes, dump cakes, cinnamon rolls in a cardboard oven -- well check with just about any Boy Scout.