Here's a complete online guide to the various burgers available out there. You might want to send your coronary arteries out of the room for entries like this:
It's no surprise that butter burgers reach their apotheosis in Wisconsin, the Dairy State. As if a juicy hunk of meat ain't enough moistness for you, folks around these parts cook the patties in butter and then slather on a hefty dose of the stuff right after it hits the bun. Solly's Grille in Milwaukee is a famous spot for this style.
The Dish 