QR (or QuickResponse) codes are everywhere in Japan, but they're just now reaching the US in large quantities. If you're looking for the next big thing for marketing departments, I have a feeling that this is going to be one of the many tools of the future.
Visit Wikipedia's page on the subject for a quick overview of the technology.
I downloaded the i-Nigma barcode reader for my Sprint Mogul and have been pleasantly surprised at how easy it was to install and use. Other readers you can try downloading are: QuickMark and Kaywa. Once you get a reader installed on your mobile phone, check out Kaywa's QR Code Generator!
Scan this code to add me to your address book.
Take a look at this code to send me a quick text message saying that you've read this page.