Dotty's is probably the best place to grab a burger in Madison. I love their southwest burger and sweet potato fries. Don't miss their shakes, which are really good. Their "sundae" is disappointing: hard vanilla ice cream with cold syrup, not hot fudge.
Every time I've eaten at Dotty's I've had to wait in their cramped lobby. Thankfully, I've always been seated quickly. Prices are average, which is nice for the student crowd.