Drop.io

Drop.io

Entrepreneur: Sam Lessin, 25

Funding: Backed by $3.9 million from RRE Ventures and DFJ Gotham

Most of the stuff we put online—from photos on Flickr to videos on YouTube—is meant for public consumption. But what if you want to share something with a select group—and no one else? Once an employee at consulting firm Bain, Lessin set about to find an answer. So he founded Drop.io, which lets users create "drops," or spaces on the Web where they can store up to 100 megabytes for free or more for a fee. Only those who have the drop's URL can see what's there. Even Google and its powerful crawlers, which comb the Web link by link for data to organize and index, can't find it. Clients include MTV and independent record labels that use drops to distribute music.

Lessons learned: "Do what you're passionate about," says Lessin, who has seen a lot of friends at hedge funds lose their jobs. "I'm working hard at something I truly love."