A friend of Beef made me aware of this interesting piece of kit recently and, if you over look some of the real world difficulties in implementing such a system, it’s really rather unique.
Semapedia.org aims to “connect the virtual and physical world by bringing the right information from the internet to the relevant place in physical space.”
The clever people at Semapedia ask us ordinary folk to print Wiki specific barcodes (that can be created using a simple online form) and literally stick them to their real world counterparts. When you see one, snap it with your standard camera phone and, Bob’s your uncle, the relavent Wiki content is sitting in your hand. (Please note, Bob may not actually be your uncle, he’s certainly not mine. Mine happen to be called Uncle Mike and Uncle Roland.)
Go forth and tag!