Create and embed QR Code images, offer QR generator to your user. Can also render Custom-QR-Codes with included logo.
I just tested this plugin for use in generating QR codes to embed in a post. It worked perfectly. And you just need to enter nothing but the data attribute at minimum. But it's nice to know that you have the ability to adjust the size, margin, background color, etc. This plugin also provides for creating QR codes by placing a QR Code editor option using a shortcode. It looks good and functions nicely. I just find the sliders for size and border a bit awkward to use.