Restaurantosaurus has one (at least it was there in Feb 2011).
They have the usual stuff, lettuce, tomato, pickles, onions, mild peppers. But the also have cheese sauce (not sure if Restaurantosaurus has it or not, I believe 1 doesn't but the other 2 yes).
Sauted mushrooms, relish, saurkraut, dressings, ranch, bbq, honey mustard..those sort of things as well.