QR Codes are not just cool but also the future for marketing, manufacturing and many other sectors. If we want to use them in our software we will highly likely have to use some libraries. For php the defacto QR code library is well... PHP QR Code. If you are also using smarty, you will find our little smarty plug in qrcode very useful.
Go to http://scalingexcellence.co.uk/qrcode_smarty for more information and the tutorial.