I consider QR codes an untrustworthy abomination and contrary to the proper philosophy and structure of the internet because they are not human readable. (I've been on the internet since before the World Wide Web was a gleam in Tim Berners-Lee's eye.) I was already planning to include the URLs for the books2read sales link pages.
I might include one QR code for the Superior Magpie Press website... I'll think about it.