A mysterious link from Jim Flanagan's del.icio.us page led me to QRコードBlog ("Not just about QR code; all the entries are in QR code"). I encountered a site with many graphics, a little bit of text in Japanese, and many odd-looking black and white mosaic images. These turned out to be QR Code, a 2D barcode developed about 10 years ago in Japan and now an international standard.
Nowadays, Japanese cell phones come equipped to scan these code with their built-in cameras, so QR code is extremely popular as a way to get data into cell phones. For example, business cards are printed with QR-encoded versions of personal data, allowing a recipient to simply take a picture of the card, and all the info is slurped into the phone.
So QRコードBlog is not only about QR code (including such eccentricities as QR implemented as chocolate sauce on a white chocolate bar), but all of the entries are encoded in QR as well. Not to be outdone, here's the first paragraph of this entry as QR:
(The image came from QR Code Generator.)