I have always been thinking on concepts that would allow actually purchasing a physical good (a coffee perhaps) in the physical world without having an access to a "computer" perhaps a watch like (or even a wristband like) device could be made so users would be able to send funds without a hassle wristband-to-wristband and wristband-to-server, a server would be a more sophisticated wristband that would allow billing on distances up to 80cm and would usually be used by businesses rather than in a personal manner, the wristbands themselves could be very minimalistic, calculator-like with 3 buttons and a led display, perhaps solar powered (they are also "green" and untraceable) since there is really no need to do anything except storing private keys and breaking up unspent transactions properly.
This could become the reality in less than half a decade. I'm just hoping I will be the one to raise the funds for it and execute it
