In the last few years, mesh networking has been transformed from a largely military application into a tool for providing Internet access to large populations. ­Meraki's Outdoor repeater ($100-$200) can transmit to other, simpler repeaters; the company has a network set up in San Francisco, with additional networks in places from Alaska to the southern tip of South America. "Some of our customers are considering blanketing entire cities with hundreds of thousands of devices," says ­Sanjit Biswas, a former TR35 honoree, who cofounded the company in 2006, drawing on research he did at MIT.

A. Weatherproof Shell
The shell of the repeater is made of a polymer treated to block UV radiation, so it can "sit out and bake in the sun for a few years," says Biswas. The green O-ring around the internal perimeter is secured with screws, which put enough pressure on the seal to form a waterproof barrier. Green cable plugs at the bottom, made of a silicone rubber, maintain a compression seal around the Ethernet cable. A working Outdoor is submerged in a fish tank in Meraki's office, to prove that it can survive a monsoon.