The best use I saw was on some small electronics thing I was looking at in a shop. One brand had QR codes on their boxes, which led to a full specification and the user manual -- more than could possibly have fitted on the box, especially as a European box can have 10+ languages.
Another is joining a Wifi network. I saw this at a couple of small hotels recently -- as well as giving the network name and password, there was a QR code. Scanning it prompted me something like "Do you want to join NiceViewHotel Wifi network? Yes/No" and was much quicker than typing in the key.
Another is joining a Wifi network. I saw this at a couple of small hotels recently -- as well as giving the network name and password, there was a QR code. Scanning it prompted me something like "Do you want to join NiceViewHotel Wifi network? Yes/No" and was much quicker than typing in the key.