29. Drew Houston & Arash Ferdowsi
Drew Houston & Arash Ferdowsi
Houston: Co-founder and CEO, Dropbox
Age: 28

Ferdowsi: Co-founder and CTO, Dropbox
Age: 26

Industry: Technology

Silicon Valley is teeming with startups, but few manage to attract some 45 million users in less than four years, as Houston (an MIT alum) and Ferdowsi (an MIT dropout) have with Dropbox, a service that lets users store and share documents and photos in the cloud. Despite growing competition, Houston and Ferdowsi's college project has been growing like a weed -- 300 million files are saved to Dropbox each day, more than the number of tweets posted to Twitter per day.

Hobbies: Houston was in a '90s cover band in college; Ferdowsi is an avid Dance Dance Revolution (DDR) player.

Last updated October 25 2011: 5:11 PM ET