I know people will scream “Big brother”, but what Path Intelligence is doing is pretty interesting.:
“Path Intelligence is a U.K. based company that monitors foot traffic in a rather ingenious way, through customers’ cell phones. Periodically our cell phones ping the nearby cell towers basically saying “Here I am”. Path Intelligence has built receivers that detect these signals and triangulate the owner’s location with accuracy of up to a meter.”
Here a full demo
I heard of companies tracking cars in parking garages or doing other fancy stuff with intelligent traffic system (e.g. during rush hours).A traffic system for humans is a great idea, still I am not sure if privacy laws in different countries will allow that.
Well, maybe self-adjusting Walmarts shelfs are not so far off anymore 
