My favorite science fiction quote is from Arthur C. Clarke: Any sufficiently advanced technology is indistinguishable from magic. That's what immediately came to mind when I found this QR Code sculpture that uses the Sun to deliver discounts.
The promotion, launched by Korean retailer Emart, put QR code sculptures around the city of Seoul that only allows you to scan their codes when the Sun casts the right shadows between the hours of 12noon and 1pm. Once the QR code is redeemed, the order is processed online and the product is then delivered to the person's home. According to Emart, the promotion sparked a 25 percent increase in sales during the lunch-time hour.
Although it was deployed in the service of a mundane chain store deal, this marriage of ancient science and new smartphone technology is truly inspired. You can see the Shadow QR Code in action in the video below.