Canadian bacon & pineapple is excellent!
Also veggie - peppers, onions, mushroom. Or spinach w/white sauce and feta cheese.
Someone mentioned egg on a pizza in Sardinia. When I was in the Navy, we spent a couple of weeks in Gaeta, Italy. Lots of mom & pop places to find there. A friend of ours had ordered a seafood pizza. On top were shrimp, scallops, and squid! The squid were small, whole, and still had their little tentacles (which curled up when cooked). I tried it, but it was too fishy for me. Good part: the pizza crusts were thick and all baked in a fire-fueled brick oven pretty much anywhere we went over there. Awesome!