Additions welcome.
  1. Stone fruit.
    Especially when paired when a creamy, tart cheese (like chèvre or sheep's milk ricotta) and a bitter green. I make a delicious plum and goat cheese pizza with arugula.
  2. Eggs
    This is becoming increasingly common, but it's still not ubiquitous. Crack a few eggs on your pizza during the last 3-4 minutes of baking (you can even do this with frozen pizza). The runny eggs make an impromptu sauce that coats the whole pie.
  3. Pico de gallo
    Use prepared pico de gallo or other salsa (even Pace will work) in place of tomato sauce. Top with a mild creamy cheese like cheddar or jack, and bake. The result is reminiscent of nachos.
  4. Almonds
    Sliced or slivered almonds add great crunch to pizza. Plus they get toasted during baking, which maximizes their flavor.
  5. Jalapeño
    Or any spicy chile. They blister in the oven and add a kick to any combination of toppings.
  6. Sweet potatoes
    I either mash them with curry powder and cover the pie with the mash, plus aged cheddar and caramelized onions, or I slice them up very thinly and top pizza with the slices, plus goat cheese and sage.
  7. Smoked salmon
    Brush a pizza dough round with olive oil and bake until just golden. Then top with slices of lox, thinly sliced red onions, fresh tomato, fresh dill, and lots of black pepper. Brunch is served.
  8. Brussels sprouts
    Slice them thinly and sauté until cooked through, then sprinkle them over the pizza before baking.
  9. Arugula
    Suggested by @ChrisK
  10. Refried beans
    Use it in conjunction with the pico de gallo! Or black bean dip for a little color contrast.
    Suggested by @eatthelove
  11. Honey
    Drizzle it on the stone fruit pizza. It make a goat cheese and blue cheese pizza with pears and drizzle the honey over that.
    Suggested by @eatthelove
  12. Corn
    I was in Copenhagen a long time ago and a generic pizza chain had corn on one of the pizzas and it was great. Never seen it since.
    Suggested by @bjnovak