The Craftsman Figure-Eight is the most versatile wrench available. Each end of the one-foot tool has two swiveling heads of different sizes. Each head's teeth grip round, square or hexagonal bolts. Craftsman Figure-Eight Wrench$25
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.