The Extreme skate park in downtown Louisville, Ky., sits between a loop of interstate highway and the headquarters of a grain company whose sign reads "Producer Feeds -- Since 1869." The park looks a little like a homemade Hot Wheels track, something a resourceful toy-deprived child might make out of flour-and-water paste. It has every feature a skateboarder could want, though. The city of Louisville, which opened the park a little more than a year ago, is hoping to attract… more