We started using them on the print pages of homes for sale that we provide for our clients. The QR links to a google map of the property's address. Usually a buyer would print out the listing and take it with them to see the house. So far it seems to be a much easier way to get directions to the house without having to type in an entire address on your smartphone.

Sample: http://virtualstagingsolutions.com/a/view/1159/print