I've always thought QR codes were an exploit waiting to happen.
Here's a box of random squres, do you want to go to whatever site it may be?
I'm amazed no one has started printing their own on sticky labels, and pasting them over the 'official' ones on adverts and posters. 'Oh look a QR code on a poster for new shiny product, click, Oh thats strange it took me to malware.r.us.'