In a new post to his blog Stefan Koopmanschap looks at some of the tools he found to create barcodes and QR codes in PHP applications (including a bit of sample code for what he found).
For a project I am working on right now, I needed to generate barcodes and QR codes. Looking around for solutions for the barcodes I quickly found Zend_Barcode (thanks to someone pointing me to it, by the way. I had not expected a barcode generator in Zend). For QR, it was slightly harder to find a good solution. A quick question on Twitter helped a lot. In the end, it boiled down to two options: PHP QR Code and using the Google Chart API.
His examples are Symfony-based, but it's easy to translate them over to the framework (or just basic script) of your choice. Zend_Barcode had what he needed for normal barcodes, but when it came to the QR side, he opted for the home-brew solution rather than the Google alternative (for reasons related to the project). Using the library is as simple as defining the image output type and the string you want to encode.