QR codes (Quick Release code) are a great way for smartphone users, who have the scanning application installed, to download 
information to their handset by scanning the QR code. The QR code will typically have a weblink (url) embedded that directs the user to the webpage of interest, which is promoted on the main visual of the page or marketing collateral. It effectively extends the life of the collateral you are producing. So it’s a great way to achieve extra web traffic, from your printed materials.
They also work well to measure how successful the information is with your target audience. A service like Bit.ly has comprehensive statistics available on the links embedded in the QR code.
Even though QR codes were developed in 1994, it is still relatively misunderstood technology, see this article here, but using them does put you in the 21st century in terms of marketing. You may just get some baffled looks as not many people know yet what they are for. Find QR code history on Wikipedia.
I think QR codes are great for directing potential clients and customers to specific information, and to make it easy for people to access information quickly to help get a better understanding of the service or product. They also work really well if you supply a direct link to enquire or use it to allow the user to download contact details. Off course, all the above applies only if you have engaging material, with a relevant call to action for your target audience. QR codes used on their own will not do anything!
There is a next step to all this, and in most professional organisations that is by a face to face meeting. So from your marketing collateral and website all roads need to lead to your main switchboard number or department head contact details to arrange a meeting. Just bear in mind that as it stands at the moment, you may not supply any contact details direct on the front and product pages on your website, so even if you are directing people there by using the QR code, you are still forcing people to navigate away from that page in order to enquire or get more information, risking that the user may lose interest and bounce. This is especially relevant with mobile marketing.
It’s worth mentioning then that QR code can also be a direct link to enquire via email or download contact details to the smartphone from which the user can call the switchboard or the department.
Otherwise the QR code is just increasing web traffic, which is great if that’s all you are aiming to achieve and not driving the enquiry, which is what you really want. Some of the other pitfalls some companies fall into when using QR codes include directing people to just the home page, which doesn’t have contact details, to links that do not work or directing them to a page that cannot be viewed on a smartphone.
So always have it that a link is mobile friendly or in case of contact details use a service like pingtags or create a .vcf contact card that is stored under a friendly url on your website server.
QR code readers are in plenty supply mostly free for most smartphones, with Google Goggles now available in Google Search, I personally use the widely used i-nigma and the relatively unknown http://createqrcode.appspot.com/
