It is not long off that anything and everything will have a digital signature. Including ourselves. Here is one of the first Australian examples from the NSW Government in which QR and NFC is used in conjunction to make people more digitally aware and informed about their physical surroundings.
With the new iPhone due in September and with the expectation it will be NFC enabled expect to see a lot more of this tech, quick! I would love to see this used in a campaign as an ARG mechanism or Treasure Hunt with each clue leading to the next etc.