Drew Houston

Houston was 24 in 2007 when he cofounded Dropbox, a company that made it drop-dead easy for nontechies to store work files, photos, and more in the cloud. The company claims more than a half a billion users of its cloud storage and related collaboration tools and is continuing its push into business accounts. To be sure, Dropbox is facing off against much bigger competitors (hello, Google), but fans say its easy interface keeps it competitive. Now, investors, who valued the company at $10 billion in 2014, are salivating over the prospect of an IPO.