Instead of using one of the tools Dr. Morris recommended, I went with something I’ve used to produce QR codes before; the QR Code Generator Plug-In for Google Chrome. It uses the code producing, well, code from the-qrcode-generator.com, but it’s a very handy little widget.
As far as using QR codes in a library, I have a personal favorite use; SCAVENGER HUNTS! Okay, yes, I realize that I’m the poster child for scavenger hunt use. My summers revolve around a massive scavenger hunt for incoming freshmen. But, think of it this way; you could use QR codes to display clues that people have to find other codes tucked away both physically and on web pages. I’d love to expand my scavenger hunt to include these.