Here are the ideas of Barbara Schroeder, Clinical Associate Professor with the Department of Educational Technology at Boise State University:
I love the interactivity piece...sending people to further information. To keep students awake during our own presentations in the library we can even put QR codes into our LibGuides and they can scan them when they are projected on the screen. I did that with my recent PREZI presentation and participants could get the direct URL for the PREZI sent to their phones.
So easy to do: just enter a URL into a QR code generator (many on the web) and then embed the image on your blog, web page, or simply copy & paste it into a word doc. The mobile phone user just needs a bar code scanner app on their phone.