My most successful application of QR codes has been on my resume. Each resume had a unique link to a page on my personal website/portfolio with some extra info (PDF download, link to github/linkedin/etc) and some analytics so I could see if it was getting any hits and what other parts of my site people were looking at.
Didn't expect much to come of it, but I ended up getting some positive remarks on it in interviews.
Than again, I though about putting a minified link to a Cv-page with extra info and a way to interact right away. And if you're looking for a job in development/design a simple base encoded url that points to a page where you pinpoint shortcomings in the Site or App/Service of the business for which you made the Cv is for.
Didn't expect much to come of it, but I ended up getting some positive remarks on it in interviews.