QR-Code

The Kaywa Reader

From Wikipedia:

Although initially used for tracking parts in vehicle manufacturing, QR Codes are now used in a much broader context spanning both commercial tracking applications as well as convenience-oriented applications aimed at mobile phone users. QR Codes storing addresses and URLs may appear in magazines, on signs, buses, business cards or just about any object that a user might need information about. A user having a camera phone equipped with the correct reader software can scan the image of the QR Code causing the phone's browser to launch and redirect to the programmed URL. This act of linking from physical world objects is known as a hardlink or physical world hyperlinks. A user can also generate and print their own QR Code for others to scan and use by visiting one of several free QR Code generating sites.