Surprised they didn't mention cryptocurrencies at all here. Scanning QR codes to enter an address when making a transaction is pretty much the only feasible option I know of. Manually entering a very long random string is too much of a hassle, especially if you'd want to do real-world transactions.
You can use an Oh By Code.[1]
From the "HN FAQ":[2]
"You don't need any software or tools to create them. You don't need a reader or an app to read them. You can write them down anywhere with any pencil, pen, chalk, etc. As of the launch of 0x.co, there is no longer any reason to ever use a QR code again. You're welcome."
[1] https://0x.co
[2] There is a FAQ but also a "HN FAQ" with more technical, implementation-minded Q&A: https://0x.co/hnfaq.html