Here's what I have when I'm really craving pizza:
1 light multi-grain english muffin (100)
1/4 cup part skim mozzarella cheese (85)
4 tablespoons tomato sauce (40-60)
Split the english muffin in half and lightly toast in. Then put it on a baking sheet and top with the tomato sauce, cheese, and vegetables. Broil this for about 5-10 minutes, until the cheese melts.
You can eat both halves for around 245-295 calories. I usually put some mushrooms and broccoli on mine.
If you want to make it even lower calorie, you can substitute the mozzarella for fat-free ricotta cheese.