Whoa cats, calm down. The hamburger is meant to bring people together, not as a tool of flame war destruction. The poor little hamburgers...
Anyway, if I have a good quality beef, I just throw them straight on the grill (charcoal, by the way). Seasoning the meat before hand is good (just a little salt and pepper). Lightly toasted buns are good, I usually just put on a cheese (usually American cheese or Provolone, sometimes cheddar) and some BBQ sauce, or ketchup if no BBQ sauce is available. Yeah, put the cheese on the burgers right before they come off the grill. Maybe I'll try some mozzarella with some Pecorino romano cheese next time.
You can find recipes for gourmet hamburgers online. Some people use blue cheese, Swiss, basically any cheese you want. I know some restaurants put blue cheese in the middle of the hamburger patty (make two patties not too thick, put some cheese in the middle of one and cover with the other. Make sure the two patties are sealed together, or the cheese will just come right out).
Listen to the posters above you, they have some good pointers.
I know people who put peanut butter on their hamburger rolls. They say its really good, but I have yet to try it.