If you aren't familiar with QR codes, I can pretty much guarantee that you've seen them around and just didn't know what they were.  QR (Quick Response) codes are similar to bar codes but can hold much more data; they enable you to pass along information to clients and prospective clients who are able to scan them with a QR code reader, usually a smart phone.  The codes can hold data such as: a web url, contact information (vcard), a Google maps location, and SMS message composers.  The sample at right contains the url to this website:  http://www.glerin.com.