Rank: 13
Stewart Butterfield and Caterina Fake
Co-founders, Flickr
Why They Matter: As the creators of Flickr, the phenomenally successful photo/social-networking site, the husband-and-wife team has become the poster couple for the Web 2.0 movement. But that's not why they appear here. Flickr was acquired by Yahoo last year, and now Butterfield and Fake have been deployed to spread some of Flickr's social-media DNA throughout the company. That means finding new ways to emphasize human-powered keyword tagging and filtering, on everything from your own search results to travel itineraries and restaurant reviews. Incorporating the subjective nuances of human judgment into its search results has become an essential part of Yahoo's strategy to compete against Google, its algorithm-obsessed rival. Thanks to the Flickr kids, the search wars are shaping up to be a battle of man vs. machine.