1. A system that mitigates privacy concerns in connection with ad targeting or data collection, comprising: a mobile communication host device, comprising: a communication component that extracts shared information from a communication transaction between the host device and a peer device; a mapping component that updates a social graph maintained on the host device based upon the shared information received from the peer device; and an advertising component that receives a set of advertisements and that selects or tailors in a privacy-centric manner a custom ad from the set based upon the social graph.