QR codes (Quick Response Codes) are two-dimensional codes that can store huge amounts of data. They are somewhat like the product bar codes we are all used to seeing on our purchases. The scanning app needed to read the codes can be downloaded for free from the following website: http://qrcode.kaywa.com/ suggested by Annette as one of the more user-friendly versions available.
Having used myself this morning to create a QR for BookCloud in only a few seconds (see above), I can vouch for its ease of use. If you're interested in experimenting with new FREE apps, especially those with smartphones or the new iPad 2 and netbooks, visit the e-Support wiki link to the left of this blog.