i love to roast a bulb of garlic in the oven.....slice off a little of the garlic that comes to a point, drizzle about a teaspoon of olive oil, wrap it in foil and roast it at 400 for about 12-15 minutes. when it's cooled you can squeeze out the garlic and spread it like butter on the pizza dough before adding other toppings. gives it a nice flavor, not overwhelmingly garlicky. yummy!
sun dried tomatoes
marinated to whatever you want it to taste cubed tofu ie. barbecue, curry, etc. you get the point :-)
shredded soy cheese
i also like to grill the dough till golden brown before adding the toppings and then bake it in the oven. it adds a nice smoky taste to the dough. it also helps the dough from falling apart if you're putting on a lot of toppings.