The data: From his computer science lab in Palo Alto, Mayer has shredded the official spin on government and consumer surveillance. His research showed that the NSA's bulk collection of telephone metadata is far more invasive than officials let on. He and a research partner found that the seemingly bare-bones data could be used to show with some certainty callers' religious affiliations, medical conditions and, in one case, a woman seeking an abortion. Before that, Mayer caught four advertising companies, including Google, flouting a Web browser's privacy feature by installing trackable cookies. He posts his revelations on his blog, a must-read for journalists, activists and policymakers.