There's a really renowned local place down here called Litton's that originated the "Thunder Road" burger--beef, pimento cheese, sauteed onions, bacon and jalepeno slices. Messy as ****, but much tastier.
I went to a little joint in Charleston, South Carolina this summer called Poe's (all Edgar Allan Poe themed... like it was designed just for me) that had some fantastic burgers with really unique ingredients and topping combinations. Avocado, gorganzola, chili, jalepeno remoulade, you name it. We even got there just before the kitchen closed down, when food is usually the most rushed and least quality, and it was still great.
As far as chain places go, Cheddar's has an amazing burger if you get it with brown sugar bacon and honey-lime sauce, and I'm also quite partial to Famous Dave's Devil's Spit burger. Caustically delicious!