Andrey Avgust's speculative redesign for America's heroically ugly paper money reimagines greenbacks as modern plastic banknotes, similar to the more daring bills in Australian and UK currency, with UV-readable serials that are repeated in QR codes with PGP-signed hashes.
They look more like high-end collectibles than fiat, and they miss an important usability aspect in that they're all the same size, rather than following the sensible custom of printing larger-denomination bills on larger sheets.
That said, they're very futuristic and beautiful.
American Money Reimagined [Troy Turner/Yanko Design]