The people over at BeQRrious.com [good domain], have a gallery of some cool QR Codes demonstrating what is possible with the level of customisation. It still impresses me the amount of manipulation the codes can withstand whilst being readable, particularly the forced perspective and squares that are no longer square! [I don’t know if the code gallery mentioned, features all codes the company have created.]

Their online QR Code generator also creates graphical codes with a logo of your choice included within the design.