Don't know what a QR code is? Better find out soon... QR codes are being used extensively in mobile marketing campaigns overseas, and are starting to make a breakthrough in the US. Quite simply, a QR code is a "matrix" bar code that was developed in Japan. The QR stands for "quick response", and is being used in marketing for mobile users to take a picture of the code or read the code with the cameras on their phones and trigger an action on their mobile phone. It could be a content download, a message or link to a mobile site.
Companies can create a QR code that's uniquely their own, and implement it anywhere their imaginations lead to do some interesting things. The only caveat is that mobile users who want to interact with the code must have a software on their phone that can utilize the camera to read the code. While phones overseas are beginning to implement these as a standard software on phones, in the US you'll likely have to prompt users to download the software. Don't fret, though, as you can have them send a text message to a short code and download it, if they're on the go.
There have been some cool campaigns using this technology. Some examples include Mind Share's use of QR codes for Northwest Airlines to collect email addresses, Singapore Air and McDonald's have also joined the list of many marketers using QR codes. In fact, recently, I saw an ad in a magazine for Sprint that introduced readers to the QR code. It's only a matter of time in the US before we begin to see this used more extensively.
One of the more recent interesting uses I've run across is QR Kill, a real-world game where players "kill" one another by taking photos of the other's QR codes, which they wear on their backs. You can read more about QR Kill at this QR Code blog.
To learn more about QR codes, you can also read this article at the Mobile Marketing Association site on QR codes.