America's major cultural gifts to the world seem to be:
in no particular order.

south park
the simpsons
peanut butter and jelly
telly evangalism
and the internet on which i write this very blog, now thats not to bad i think.

other things they are famous for such as slavery and cultural imperialism were learn't and learn't very well in fact from other countrys like england for instance.
however i left one thing out of the list, America is responsible for the biggist and bloodyest terrorist attack in the history of man kind [yes thats right bigger than 9/11] America has given to the world one of the most terible concepts ever invented, nuclear war, nuclear holocaust, megadeath [a million deaths all in one go]
the bombs thrown onto hirroshima and nagasaki, the destruction, the death, the desiese proliferated for generations by the radiation which they claimed to not know about but in fact did, the biggest action of mass murder ever perpetrated.