From the day Aimee Woodall started her marketing firm, the Black Sheep Agency, in Houston in 2009, she knew success would depend entirely on breaking with what she calls "agency culture." "It's a lot like legal culture," she says. "You're tied to billable hours, and you're always grinding."

So she threw a wrench into those gears. Black Sheep has no formal policy around flextime or working from home, and offers unlimited paid time off. The only rules are to respect your colleagues, respect the work, and overcommunicate. Woodall says it's better for clients, too. Such flexibility "keeps our energy levels high, so everybody can bring 100 percent, and helps us stay efficient," she says.

About six months in, Black Sheep worked with a large Texas nonprofit, and Woodall saw her whole team change. "Everyone was really excited," she says, even when they were working at midnight. Wouldn't it be great, she asked, if they could do that kind of work all the time? Over the next two years, Black Sheep made that switch, and now works only with cause-driven clients. "Our number-one goal is to be ahead of the curve, on the edge, experimenting the way we were 11 years ago, when everyone said we were crazy," says Woodall. "When you're asking your team to do that, it makes you look at business differently."