Sandy Jen & Elaine Wherry

Meebo.com is already defying expectations for its against-stereotype leadership team. Of the company's three co-founders, it's the two women who bring the engineering chops. Sandy Jen and Elaine Wherry, with degrees in computer science and symbolic systems respectively, teamed up with fellow Stanford alum Seth Sternberg (MBA) to start Meebo, a browser-based, all-in-one instant-messaging service. In 2005, Jen was frustrated with having to remember all 13 screen names for her various instant-messaging accounts, and after fiddling around for a few months with Wherry and Sternberg (and leasing server space with their personal credit cards), Meebo was born. These days, Meebo claims 140 million users and has been valued in the hundreds of millions of dollars. Nielsen/NetRating has named it the fastest growing instant-messaging destination in the U.S., ahead of Google Talk and Skype Messenger. "We think about the Internet as an ecosystem, not a loose collection of sites," says Jen. "There is so much you can do once you are able to connect users in ways they want and need."