QR code stickers are almost as easy to make as a QR code. All you need is a generator and sticker paper which you can buy at pretty much any store that sells paper or crafts. I got some at Office Max. So once you create a customized code using a generator, all you need to do is set up your printer so it's aligned with the sticker paper and print.
These are also a great marketing tool. A lot of companies hand out stickers with their business logo on it, so this is an even more interactive way to give out free stickers. I think these could also be a great cataloguing tool. Instead of writing out categories, you could have A QR code that links to text.
I wouldn't be surprised if QR codes become huge with skateboarding companies, since they rely a lot on sticker marketing. When I used to skate, I would always put stickers on my board of my favorite brands. It doesn't seem like a big deal, but it's actually a great marketing idea to give people stickers with a brand name, or now with a brand QR code on it, when they purchase one of their products. A lot of times people will use those stickers, and then it's free advertising.
Also, bands trying to get their name out will hang out a lot of free stickers. If they hand out some with a QR code linking to their site that has a few of their songs available for free, this could quickly increase their popularity much more quickly than just a sticker with their band name on it.