This is what I made for my family the other night and they were a huge hit.
This is what you need:
Grilled chicken: seasoned anyway you like, diced
shredded mozzarella cheese
red onion: optional but highly recommended
fresh diced tomatoes: not from a can
small french bread rolls: these ones can be found at Sam's Club
Put the pizzas under the broiler on the middle rack and melt the cheese to your likeness.