Most robots are made of metal or plastic. They are solid, hard devices. Occasionally someone will make a robot that is covered with a soft skin, but underneath they are all made of rigid components. What would happen if you made an inflatable robot? You could use pneumatic power, valves and pumps to make it move. This is exactly what Saul Griffith is working on and it is quite interesting stuff. Take a look at the video from the Solve For X conference.
By the way, this is also the guy who wants to use kites to generate power. Another cool idea - shown in the video below.