QR Codes
A QR Code is a two-dimensional barcode that can encode arbitrary binary data.
Stick one on a physical object encoding a link to a page that can be configured to 301 to arbitrary URLs (e.g. https://www.noisebridge.net/qr/07A72C23A7), and you get a system for hardlinking physical objects into cyberspace.
- The Wikipedia page on QR Codes is a decent overview.
- The ISO standard (208.00 CHF, ~$180 USD) developed by the original manufacturer, Denso Wave.
- Overview on Denso Wave's site
- Zxing Project appears to be a Google-blessed software library written in Java for processing one-dimensional and two-dimensional barcodes. It is written for use on mobile phones.
- Snappr.net has an image-attched-to-email-to-text type gateway setup. snappr [at] snappr.net More info on their page
 Other 2D Encodings
- Xerox PARC Dataglyphs - Embedding binary data inside of image dithering. Neat trick.