Smartpox.com is an interesting crossover between the online and offline worlds. The technology allows users to encode URL links, phone numbers, email, and text into 2D barcodes. These codes can then be read using a cameraphone running the J2ME Smartpox reader. So a Smartpox is essentially a 2-dimensional barcode, which contains data that can be decoded using the Smartpox reader in a mobile phone.
The goal of Smartpox is to be a "viral messaging" application, allowing people to link their online world with the offline world. The use case given in the demo is of music band's website, which features an audio file of one of their songs. The band members could encode the URL of that song using Smartpox.com and put it on flyers for their next show. When a Smartpox user sees the flyer, they could scan and decode the "pox" containing the song URL and listen to it on their phone. The link is also saved under that person's profile on Smartpox.com.
So Smartpox in a nutshell enables people to create encoded messages of online content - to be discovered in the offline world. There are social networking aspects to it as well, because whenever one member sees another member's Smartpox using their phone - the link is saved to their profile and they can discover who created it, read more details, and add comments when they return to the site.
I like the idea of a 'real world' hyperlink that connects something in the online world to people in the offline world. Because it requires both online signup on Smartpox.com and a camera phone with the Smartpox reader installed, it'll probably be difficult to get network effects going - unless it becomes popular in an existing social network like MySpace. But the idea has promise, particularly for the mobile phone-wielding MySpace generation. Certainly it looks like a sign of things to come, with its online-mobile-offline mix.