You can use this feature if you find a QR code while browsing the Web with your Android phone (go to Menu, More, Share page, Decode this QR image).

NeoScan is a lightweight, browser-based QR code image scanner built with HTML, CSS, and JavaScript. Upload QR images and instantly decode their contents with this simple, intuitive web application.

Furthermore, there is a possibility of generating QR code images for already encrypted text so that only a particular application can read off an image — that is, using a custom QR code decoder ...

How to Scan a QR Code on a Droid. A Quick Response, or QR, code is a square barcode designed to hold much more information that a standard barcode. Since most mobile phones now come equipped with ...