Joe Gebbia, co-founder of Airbnb, is creating a startup called Samara. Samara focuses on backyard houses given the increase in families in the U.S. living under the same roof. The backyard houses come in two sizes, 430 square-foot and 550 square-foot, and can generate excess electricity. "We made it really tight, really well engineered, and really efficient," says co-founder Mike McNamara. The backyard houses can be used to accommodate in-laws, provide office space, or serve as a rental.