f you want to use QR Codes for business or marketing purposes then you should consider that people have higher expectations from scanning a QR Code than they do simply clicking a link on a website. You should offer something special or unique to people that have taken the time and effort to scan the barcode. For ideas of what this could be, or just for more information about QR Code Marketing have a look at Piranha Internet who have successfully incorporated the use of QR Codes into several marketing strategies for their clients.
Also remember that many people won't know what a QR Code is or how to use it. Up until their use is more widespread you will need to provide instructions about what to do with a QR Code.