Add green or yellow peppers, onions, tofu cubes, pineapple, shrimp, or any other grill-able foods you or your guests might enjoy to the mix. Just be sure to increase the amount of sauce or rub you use as needed, and grab more skewers.
Then, you can either grill the chicken separately or let people literally build their own kebab by putting the ingredients they desire on their own skewers.