The entrepreneur and one-time Obama staffer is putting his digital prowess to good use—literally. Having worked for Barack Obama for three years—running the former president’s Twitter account, no less—Caleb Gardner is no stranger to mission-driven work. But in recent years, he felt that digital efforts in that realm had sometimes been misguided. With his startup digital consulting firm 18 Coffees, he is “hoping to blow up the way people think about how digital problems are solved,” he says. The catch? He only takes on clients doing purposeful work.