Quiches-you can do broccoli and cheese, spinach and cheese, ham and cheese, bacon and cheese...
Salad-Caesar salad with cooked chicken or shrimp (you can get Perdue done its for already cooked and sliced chicken)
Tortilla/Flatbread rollups-you can make them yourself or purchase frozen (or if you live near a Costco they have fresh ones that you could slice smaller)
Stuffed breads-pizza dough with fillings. Sausage and cheese is my favorite, but I've done Broccoli and Cheese, Meatball, Chicken or Eggplant Parmesan (used frozen chicken patties or frozen breaded eggplant) with sauce and mozzarella, roll up and bake for about 30 minutes, then cut into 1" slices
More appetizer type foods-pigs in a blanket, mini meatballs (in a grape or currant jelly and chili sauce), pizza bagels, kielbasi (cook in apple juice and then coat with some apple jelly, cut into coins).