"CityWare" is a new service, currently in development, that could eventually help you find out more about the good-looking individual that you see on the train each morning.
The project is designed to help people find out more information about "familiar strangers".
A team of UK researchers, with backing from Nokia, HP and Vodafone is creating CityWare, a Facebook application, that uses Bluetooth to find out more about people around you.
Created at Bath University the tool can use the unique ID of Bluetooth devices, like a mobile phone, to build new "friendship networks".
Dr Vassilis Kostakos, at the University of Bath, said:
"Most people you bump into or see regularly have made information about themselves available publicly online."
"But the Internet is such a big place that it's difficult to find contextual information about who someone is, where they are, etc."
CityWare lets users discover if the people they see regularly are also Cityware usera and have a profile of Facebook.
It's a while off from becoming mainstream - to get involved in the scheme you'd need a Facebook account, the CityWare application, a Bluetooth device and be near a CityWare node.
At the moment nodes have been set up in Bath, University College London, the University of California in San Diego, with more nodes going online in Sweden, Hong Kong and Sydney.
These nodes scan for Bluetooth-enabled devices in a given area, and send that information back to servers which compare the IDs of the gadgets with any enabled Facebook profiles.
Dr Vassilis Kostakos explains: "When you return to Facebook you will see a list of all the devices you were near and the link to profiles of people who have tagged themselves on CityWare".