Stack it up!

[Polaris]

KETCHUP, KETCHUP, KETCHUP

[Goldenboko]

two patties, lettuce, BACON, cheese, mustard, ketchup, pickles, and a bit of onion

Grr.... forgot bacon too... I shoulda included other.

[NorthernChaosGod]

Two patties, lettuce, tomato, ketchup, mustard, mayo, and lots of onions.

[Vincent, Thunder God]

Depending on the burger, it's either cheese only, or cheese and ketchup (that's how Canadian's write katsup... the way it was spelt in the poll was the British way I think).

[Zeldy]

Its very rare I have a burger, but when I do, it always has Tomato Ketchup on it, and cucumber and lettuce.

Id rather have a subway!

[Yooniece]

The meat's important. Has to be tender and flavorful.

So meat, swiss cheese, sauteed mushrooms, fresh red onion, tomatoes, lettuce and 1000 island dressing.

[Odaisé Gaelach]

Meat, cheese (lots!), ketchup, and onions.

[oddler]

This reminds me of the time my FFXI party asked this and my answer was (and remains) "Meat and cheese, baby!"