Funding: $5 million from New Enterprise Associates and Sequoia Capital.
Altman has a knack for navigation. At Stanford, he wrote code for an autopilot system that could teach a model helicopter to fly. As co-founder and CEO of Loopt, he specializes in software that helps friends find each other. Currently, 100,000 subscribers of Sprint Nextel's Boost Mobile service have signed up for Loopt, which uses the Global Positioning System chip in phones to alert users when pals are nearby. Altman left Stanford after his sophomore year to start Loopt. “School will still be there in a couple of years,” he says. For now, he'll be busy enough fending off competition from the likes of Google and EarthLink.
Lesson learned: “There are some days when it looks like everything is going to blow up and other days when things look insanely good,” says Altman. “If you let that get to you, you never actually get any work done.”