As well as being able to compare prices of stuff in the shops with a quick scan of the barcode/QR code, you can create artworks, as artist Scott Blake has shown with his series of famous faces.
A big artwork of Elvis' face comprised of QR codes can be read by a smartphone, linking the user to music by the one and only Mr. Presley. Blake also uses other types of barcodes for his famous faces—for example, Bruce Lee and Marilyn Monroe are made up of barcodes from DVDs of their movies, and Oprah's beaming face is created by ISBN barcodes from the Oprah book club. A message about commoditizing celebrities, or just a really neat art idea? [Scott Blake via Illusion via DudeCraft]
This video below shows what happens when you scan one of the QR codes (thanks, Baldbeaver!):