The first things that occurred to me for the list were jazz and American popular song.
It occurs to me that a better choice is the Internet. Certainly the Internet was invented in America. Fundamentally, it is the set of standards for interconnecting physical communication networks, and as such is intangible. The Internet is not only an important heritage of mankind, but it is in fact used directly by a billion people around the world, and indirectly affects us all. It may in fact be imperiled by its own success.
A useful point to be made by such a submission is that World Heritage items need not be old nor quaint.
(The opinion expressed in this posting is the author's alone, and should not be considered to represent that of Americans for UNESCO.)