Here's a physical one — http://hackaday.com/2012/10/29/qr-clock-is-unreadable-by-humans-and-computers-alike/ http://hackaday.com/2012/10/29/qr-clock-is-unreadab

Here's a physical one — http://hackaday.com/2012/10/29/qr-clock-is-unreadable-by-humans-and-computers-alike/ http://hackaday.com/2012/10/29/qr-clock-is-unreadable-by-hum...