QR codes are great when they contain vCard information. We love it when they are printed on business cards because you can just bust out the QR reader app on your iPhone and save the contact automatically. It eliminates the need to key in each name, address and phone number in manually.
But what happens when you run out of business cards for the day, or just neglected to carry some around with you? Drew Moxon sent us his solution: A QR code printed on a sticker placed on the back of his Leverage back plate. 
He emailed his motivations for using his phone a business card:
As a designer, I love making business cards, but hate bringing them with me. The QR code helps brand myself as a mobile specialist in games, ux, media and web. It was only fitting.
Seems like a pretty good idea to us.
Graft Concepts 