I wouldn’t say it’s exactly creative, but a common useful application of qrcodes is for communicating wifi network names and passwords. If you use a GNU/Linux distro with NetworkManager, wifi-qr is a nice tool which can not only scan but also generate these phone-compatible wifi qrcodes for any saved wifi network your computer knows about. On debian-based distros, just apt install wifi-qr and run the wifi-qr command and you’ll get a qr code right there in your terminal which you can scan with a phone.

edit: actually NetworkManager’s commandline tool generates the QR codes itself, so you only need wifi-qr if you want to scan them. Just run nmcli dev wifi show.