I make these often for parties. You can have several different filling combos which are nice. Here are a few ideas:
* Spinach, mushroom and either feta or mozzarella cheese
* Bacon, onion and cheddar
* Smoked turkey and swiss cheese
* Sundried tomato, fresh basil and mozzarella
* Carmelized onion and manchego cheese
* Ham and either swiss or cheddar cheese
* Turkey and Bousin cheese
* Artichoke, garlic and parmesan cheese