A friend just posted me a link to this story about QR codes being used to tombstones. Hmmm, ok, nice idea...maybe...  but what if your dearly beloved departs from this world and you become administrator for their QR code linked site, and what if... posthumously they really piss you off (like giving all their millions to a cat instead of you), you could post all kinds of defamation up there, and think, no retribution!! Unless of course you believe in ghosts...or hell.  Oh,  I can really see this being a quagmire for all sorts of ethical arguments.

Wild imagingings aside and on a more practical level; as yet QR code technologies haven't really been future-proofed. They may not be around say, in a few hundred years. I can just imagine future archaelogists stumbling across a whole graveyard of QR code tombstones and thinking WTF? then making up some wierd theories to try and explain what all these  black and white squares are.