Oval track racers use these to offset the wheelbase from side to side. Mostly used on dirt tracks. They will set up a slightly longer wheelbase on the right side of the car and a slightly shorter on on the left side. As the night progresses and the water content in the dirt changes, they can alter the turn in characteristics of the car by altering the wheelbase.
Like chryco said, the only advantage to a drag application would be to gain tire clearance or square the diff. Otherwise, they have no advantage over simple blocks.
