DIY QR Codes
A great post from Tokyo Mango has coverage on a tech product that most Americans do not know exist. They are called QR Codes, the funky blocky things found above. What you do is take a picture with your cellphone and it can transmit data such as web addresses, phone numbers, pretty much anything. The main use is to link to a URL that will then have info on the item you are looking at.
Above is the QR Code that will take you to yours truly. These things really are everywhere in Japan, from Coke machines to in the supermarket. Some people even get QR Code tattoos so that someone can pic thier tattoo and find out stuff about them, like that they are into tattoos and QR Codes.