We’ve been hearing about the coming revolution of location-based services on our mobile phones for years, but yesterday’s announcement that Sprint signed a deal with the self-described “social-mapping” company loopt could help those grand prognostications prove true. By taking advantage of the GPS capabilities in certain Sprint phones, loopt allows you spot the location of friends and family members on a map, and easily text them to figure out if you want to meet. Last year the service became available on Boost Mobile, and could pin people down to within 30 feet of their precise location, but Sprint has the capacity to deliver it to far more users. And don't worry, you're not always on the grid. With the loopt service, you can switch yourself off to your approved network if you don’t want friends tracking you down—or your wife discovering that you’re not really working late at the office. —Gregory Mone
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.