http://denCity.net
denCity.net creates virtual networks of real places.

QR-codes (2D barcodes) are used to tag buildings and urban sites. your mobile camera phone can read these tags. simply shoot them and log in to denCity.net. denCity.net provides information to the specific place.

Smoothly combining the virtual with the real, each tag in denCity.net has a physical location. A map can be underlaid to allow easy orientation, even substituting a navigation system! There is no need for GPS, RFID and thelike: Each tag has its own coordinates by which the keitai knows its position.