Yes, I use Avery Labels. Still looking for an alternative because I would like to have smaller ones so I can stick them to very small stuff but the smallest square label I have found so far is 20x20mm

exactly. ^^

noteqr.de

Glad you like the idea. I actually started selling these QR Codes readily printed, but you can also do it yourself with some technical skills. The QR Codes are generated and printed before their purpose and content is known. You just scan a new code and have a markdown / rich text editor where you can put any text and attach images or files.