QR codes appear everywhere these days. They are a slick way to get an immediate response from people via hand-held media. You can take people from a walking around experience to an online environment like your website or a way to email or even call a phone number your pick for them to dial.
If you have a Google account or an iGoogle homepage, a QR code generating widget can be added and instantly accessed from your computer.
HT: SEOSearchMedia Blog