Quick Response (QR) codes also known as hardlinks or physical world hyperlinks are a popular type of 2D barcode introduced by Japan based Denso Wave, Inc. in 1994 as a powerful medium for storing and exchanging meaningful information inside black & white images.
These QR codes are the most space-efficient of all of the two-dimensional codes as they can carry meaningful information in both vertical as well as the horizontal directions and are thus capable of storing several hundred times the amount of data stored by ordinary bar codes which are just capable of storing information in horizontal direction. 
In QR Codes you can encode and store up to 7,089 numeric (or) 4,296 alpha-numeric (or) 2,953 binary(8 bits) (or) 1,817 Kanji/full-width Kana characters that can be anything like your contact information, telephone number, blog/website URL, SMS, email address, or any other normal text. The QR code images thus formed can be read by dedicated QR code readers and camera mobile phones having appropriate decoding software that can photograph QR codes and decode them.
QR Code Generator from ZXing (pronounced "zebra crossing")
Nokia QR-Code Generator for Mobiles
Duncan Sample 'Mobile Barcoder' Add-on for Firefox
QR-Code Generator Tool @Mobile-Barcodes
NFG Games QR Code Generator
Now, for decoding and reading these generated QR Codes you need the following
Get the iPhone App @iMatrix 2D Sense Platform
Windows "Standard" Decoding Software from 2D Technology Group
(Download Brochure and User manual)
Nokia Code Reader Application for mobile phones
ZXing Decoder Online
"Wonderful Tech. Stuff" QR code
These QR codes are the most space-efficient of all of the two-dimensional codes as they can carry meaningful information in both vertical as well as the horizontal directions and are thus capable of storing several hundred times the amount of data stored by ordinary bar codes which are just capable of storing information in horizontal direction. 
In QR Codes you can encode and store up to 7,089 numeric (or) 4,296 alpha-numeric (or) 2,953 binary(8 bits) (or) 1,817 Kanji/full-width Kana characters that can be anything like your contact information, telephone number, blog/website URL, SMS, email address, or any other normal text. The QR code images thus formed can be read by dedicated QR code readers and camera mobile phones having appropriate decoding software that can photograph QR codes and decode them.
Here are some of the popular resources for Generating QR-Code
The KAYWA QR-Code GeneratorQR Code Generator from ZXing (pronounced "zebra crossing")
Nokia QR-Code Generator for Mobiles
Duncan Sample 'Mobile Barcoder' Add-on for Firefox
QR-Code Generator Tool @Mobile-Barcodes
NFG Games QR Code Generator
Now, for decoding and reading these generated QR Codes you need the following
Dedicated QR code readers & Decoding software for Java enabled built-in camera cell phones
The KAYWA Quick Response Code Reader for Mobile PhonesGet the iPhone App @iMatrix 2D Sense Platform
iPhone App QR-Code Reader
Windows "Standard" Decoding Software from 2D Technology Group(Download Brochure and User manual)
Nokia Code Reader Application for mobile phones
ZXing Decoder Online
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Great posting! You might enjoy visiting a new site, www.2dcodeme.com. It's dedicated to making 2D and QR codes accessible to the average consumer, not just the early tech adopter.
The videos are professionaly produced, and the code generator on the site works perfectly......and ties instantly to sites where you can use the code on T Shirts, Tank Tops, Business Cards and Temporary Tatoos.
It's not my site....but it's very cool. www.2dcodeme.com
Thanks for sharing that useful resource Don, really appreciate it.