A neat example of QR Code execution...

Pour yourself a full pint of Guiness in this glass and reveal a QR code.  Scan the QR Code, and it will "tweet about your pint, update your facebook status, check you in on FourSquare, download coupons and promotions, invite your friends to join you and give you access to exclusive Guiness content."

http://www.adweek.com/adfreak/guinness-qr-cup-reveals-scannable-code-when-full-140602