I like the idea of P2P mobile phones, no service provider required. Phones connect directly if in range otherwise they hop via other phones to reach their target. Phones that are hopped through get paid a fee for acting as a relay. So you earn while acting as a relay and spend when making calls that need to go through other phones. I'm not sure if this could work with bitcoin, the main question is "can a phone acting as a relay be sure it will get paid?" It can't wait for confirmations, that'd not work. So can it work with bitcoin?