http://www.mstrpln.com/asrd/
(((No, they don't really exist. I'm a science fiction writer, so I actively PREFER gadgets when they don't exist.)))
Link: MSTRPLN x UBIQ - ASRD™ A STEP IN THE RIGHT DIRECTION.
About the ASRD™ Project
"The idea of footwear was pushed further by converging elements of digital culture with fashion and design into a wearble technology. The end product is a sneaker designed to detect Wi-Fi wireless internet hot-spots wherever the user may roam, with every step."
(((On the other hand (or foot), it would take your average Arduino fiend maybe two hours to cobble up a pair of these.)))
