24 hours of lemons is endurance racing for less than $500 cars, aka crap cans. it was started about 5 years ago in the SF bay area, California. It has grown to about 26 races per year, all around the country. It focuses more on the funkiness of the cars, and celebrates the weird car more than the fast car.
Chump Car is a similar serries that also started in the SF bay area, a couple years after 24 HoL. It has the same basic rules, cars cost less than $500 as raced (but all safety items are excluded, roll cage, belts, seat, brakes, tires). CC is more about racing to win, although they do give trophies for cool engineering and funky cars.
its great fun for any home mechanic who has ever thought about racing, but was scarred off by the big $$. go to the web sites and read the rules in detail, you'll understand more. PM me if you have more questions.