QR codes are appearing everywhere. I downloaded a QR scanner onto my phone and I have now started zapping away. I haven't yet scanned anything where it was actually useful but then I haven't had the scanner long enough. I created a QR code for our library (although one of the presentations on QR codes said that they should link to active pages and not just a web link!) and it worked.
I think this is definitely worth exploring especially for providing links to ebooks and online guides etc. Something to add to my TeuxDeux list!