Pizza bases (Turkish bread and naan bread also work well)
Pizza sauce
BBQ sauce
Mozzarella cheese
Pesto
Olives
Baby spinach or rocket
Fresh or sun-dried tomatoes
Fresh or roasted capsicum
Avocado
Pepperoni, salami, chorizzo
Bacon or ham
Cooked chicken
Pineapple
Mushrooms
Red onion
Fetta
Roast Pumpkin
Raid the fridge and pantry for more ideas.