Mobile hotspots are already useful, but what if you got rewarded for being a good samaritan? That's the idea driving the research project called Air Mobs. If you share data, you'll get credit for usage down the road. MIT's Viral Spaces research group has developed a peer-to-peer wireless tethering system that encourages users to share as much as they use. The Air Mobs app runs in the background, and decides the appropriate time to turn on and off WiFi sharing to the world.