I'm still very amazed on how few useful things I could find that lend themselfes to sense substitution.<p>It is really easy to map a compass to a vibrating belt (someone did it) and learn to feel it instinctively.<p>But for useful things: Either the sensor is too big (like radar, might be changing right now), or the bandwidth to high (most camera things) to sense through the skin or ears (you don't want to occupy a whole eye), or it's just not useful (e.g. infrared thermometer to vibration for remote temperature sensing).<p>Our body is made for this world, it's pretty good at sensing it.
The "Where This Is Headed" section sounds mostly like science fiction to me. But, hey, if someone does figure out how to give people the ability to photosynthesize from sunlight, sign me up ;)