"You don't have to rely on people remembering 'Oh yes, I need to do some shopping' and going to your website."

In that sense, the wall scanning is a bit of a gimmick; the critical thing is to remember you want/need to buy something.

FreshDirect, for example, does have an iphone app, but without the visual reminder, you may forget to order.

"If you can be the middleman who standardizes the protocol which lets anyone buy anything and get it delivered to their home, just by scanning a QR code, you'll make a lot of money."

That's an interesting idea: tie a QR reader app to someone's credit card or banks account on one end, and to an automated shopping cart on the other (assuming the QR links back to a specific product, of course).