I've often wondered about this type of occurrence, even imagining a tracking device that would one day make it possible for similar encounters. (This was before smart phones.) So here we are today, and that which I wondered is now possible. I guess now I'd envision an app that records your location at certain intervals and stores them in an archive. As an ice breaker, you meet someone and the app would match up any data points with that person's phone and returns time, date and location of when the two were ever the closest to each other, or attending the same event.<p>Of course with the increased worry of privacy concerns, I think it would have a hard time getting off the ground. With that considered, the app wouldn't broad cast your locations, and when pairing, it wouldn't transmit everywhere that you have been; just one or two instances where the two were standing right next to each other and didn't even know it.