Sports evolve as people do. When time and place is limited there are always creative people who bend the rules and change the normal playgrounds of a sport. Which ones began as street baseball in the streets of the US had many followers in street football (pannafootball) and street golf. Of course new sports developed as well in the world ( i.g. Parkours) and made the city a new sportsarea. In the german based newspaper there is an article about active subcultures with a (for me) new phenomena bike-polo. if you google around a bit you find some nice pictures and stories.