34. Ben Rattray
40u40 main ben rattray
Age: 32

Founder and CEO, Change.org

Almost everyone knows of Trayvon Martin, whose killing in Florida this year ignited national outrage, but few know of Rattray, the man who helped make his death a cause célèbre. Rattray's five-year-old site, Change.org, took off last year and now counts more than 20 million users, generates a jaw-dropping 15,000 petitions per month, and will bring in some $15 million in revenue this year, mostly from nonprofit advertising. Victories include persuading Universal Pictures to add an environmental message to the promotional website for The Lorax, pushing Seventeen to vow not to Photoshop out its models' curves, and enabling Martin's parents to draw 2 million signatures on a petition that even pulled the President into the ensuing fray.

Hot wheels: Rattray still drives a 1996 Toyota Camry.

--Anne VanderMey

  @FortuneMagazine - Last updated October 17 2012 05:11 PM ET
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