A few effective campaigns and some not so much, but you can learn from bad examples too:
(snippets regarding the importance of code placement and explaining the relevance/purpose of the QR Code)
Prang Power: “The quick response code provided a mobile friendly experience and the ad itself explained exactly why a consumer would want to scan and how the program works in three easy steps.”
Sleep Number Bed: “This was placed in a position that could be easy to scan, it was clear why the consumer should scan, and it was easy to use. This is among the ideal ways in which these barcodes could be used.”
Bootsy Bellows: “printed a QR code onto the pictures that were printed out. Once scanned, the smartphone user was automatically directed to the night club’s FaceBook page.”
Keller Williams: “the barcode was accompanied by instructions for scanning as well as information about what the device user could expect to obtain by doing so”
There are several more interesting “QR Code Detective” notes.