Uber CEO Travis Kalanick.

Travis Kalanick

Founder and CEO, Uber --Cultural impact
--40 Under 40 It was a breakout year for Kalanick, whose car service app became a household name. His private company reportedly is valued at $3.4 billion. Photograph by David Paul Morris — Bloomberg/Getty Images
  • Age
  • Title
  • Company

City dwellers don’t have to flail their arms to hail a taxi thanks to Kalanick and co-founder Garrett Camp. Their smartphone app Uber lets users summon a black car or cab with a tap on a virtual map and track the driver’s ETA. Uber is already available in 42 cities, from New York to Taipei, and isn’t slowing down, despite noise from regulators: A new round of $258 million in funding values it at $3.4 billion (see Uber feature story).