A few years ago, I stopped by an EAA hangar to check out the 1911 Curtiss Pusher that they were building. Afterwards, while researching it further on the internet, I discovered that the most famous Curtiss Pusher pilot was a woman named Ruth Law. She was a household name in the 1910s and early 1920s, setting several aviation records, and then touring the country with Ruth Law's Flying Circus. She made a fortune at state and county fairs thrilling the crowds with various flying exhibitions and attractions like racing against automobiles. Here's a picture of her doing what she did best:

As airplanes got bigger and faster, requiring longer runways, the airshow evolved into a fixture of airports. However, I think you could go back to the stunts and exhibitions of the early 1900s using ultralights, and perform once again at county and state fairs, and make some really good money doing it.
The law allows it because racing is certainly a sport!
From FAR 103:
§ 103.1 Applicability.
This part prescribes rules governing the operation of ultralight vehicles in the United States. For the purposes of this part, an ultralight vehicle is a vehicle that:
(a) Is used or intended to be used for manned operation in the air by a single occupant;
(b) Is used or intended to be used for recreation or sport purposes only;
...
So, should I buy a few ultralights, hire some pilots, and get a promoter to start contacting the governing boards of all of the fairs, or should I throw some more logs in the wood stove and take a nap on the couch and dream of other improbable ventures?


, but I finally got my answer. The FAA referred me to Advisory Circular AC 103-7, which they said addressed my questions.