Who are the people around me?
Say you have a magic app: you can see some interesting facts about people around you. The person enters some interesting info on his app, e.g. he visited France, he know Discrete Math, or his birthday is today. Say he notes that he is blond to be recognized.
Now you open your app and see a list of things about people around you in a list in your app, e.g. That person in black is just from China, the guy in jeans paints really cool and can you some samples...
You can also enter some info, so people may find it interesting and try to find you to talk.
Location is found by 3G or WiFi.
How does it sound?