Proximity Commonality Mobile App - Iphone app using NFC to allow you to see who in an event you know through your connections, following, or friends. Also shows friends in common that you both have.
You can walk up to someone that you just meet and with one notification see who you both are friends with. This can also be used to show a commonality graph of sports teams, television shows, organizations, music, and other activities that you and the stranger have in common, instantly.
