A patty.

A nude server.

Just cheese and ketchup.

I don't think it necessarily needs anything specifically, except maybe cheese and a bun. There are certain things like pickles, and mustard and ketchup that I really like on burgers, however certain types of burgers prove they don't need such things and can be totally great without them. Look at the Western Bacon Cheeseburger, it's not your traditional type of hamburger yet I think it's still totally awesome without the more common stuff. As for traditional burgers, I really enjoy lots of sliced up pickles, but if it's some fancy restaurant burger, I'm down with whatever.

Meat and Ketchup.  Everything else is just making it even more awesome.

It needs a bun, and I'm good to go.

jus give me a fatburger.

Cheese, ketchup, and lettuce.

Onions (Sliced finely, we talking like 25mm^2), pickles (2 preferably), ketchup and mustard

Ketchup, mustard and onions, I will have other stuff if I feel in the mood for it.

beef, cheese, bacon, BBQ sauce, more beef and cheese

Great? As in "above the average in burger goodness"? Hmmm....

Bacon, eggs, and glazed doughnut buns! :P

No, uhm. Chilly. I love chilly cheese burgers.

For it to be great, it needs to be home made.  Toasted bun.  I make my burger so many different ways, they are all great if I make them for myself.  Sonic and what-a-burger  burgers are so good, I don't even have to get cheese on them to love 'em.

Two patties, cheese, bacon, mayo, ketchup, onion and pickles. Rings on the side, root beer to drink, and it's a party.

Cheese and some cheese.

Cheese, Bacon, and Ketchup.

must have cheese, onions, mayo and gerkins

Steak sause, mayo, mustard, pickles, cooked onion, lettuice, tomatoe, and cheese. I feel too guilty to put bacon on a burger (that just crosses the line from awesome meal to shameful indulgence).

Bacon and Cheese.
Although if it's an In 'N' Out then I'm fine with just cheese.

I'll eat practically any burger that is shoved in front of my face, but I have two favorites -

a) Pickles, onions, lettuce, mustard and either swiss or cheddar cheese.

b) Crumbled blue cheese, applewood smoked bacon, and sauteed mushrooms.

Onions and cheese are a must for a great burger.

Some Dude's Fry Sauce. Seriously, go to Albertson's right now and buy some (only place I've ever seen it). It will literally change you life, and you'll start to have it on EVERYTHING.

Everything. I love EVERYTHING!

Bacon and cooked onions