Meat on a pizza is an option for some. Sausage and meatballs are both traditional toppings and should be cooked beforehand. Pepperoni, ham and other cured meats do not need to be, though delicate sheets of air-dried beef or pork should perhaps go onto the pie midway through or at the end of the cooking process, lest they dry out in the heat.
Anchovies are a marvelous addition to pizzas, and so are clams and mussels, even sheets of smoked salmon, particularly when paired with crème fraîche and capers.
Making a fried egg breakfast pizza is not for freshman-class pizza makers. Sliding a pizza topped with a raw egg into a hot oven takes patience and practice. In the meantime, while your pizza is cooking, gently fry an egg in olive oil in a small skillet on the stove, and when the pizza is done, slide it gently on top of the pie.