Mashable reports on a material called Power Felt which acts as a power source by reacting to changes in temperature.  The power output is small but can be generated using many possible mechanisms including your own body heat.  Still largely in development, this economical fabric – made from carbon nanotubes embedded in plastic fibers – could eventually be used to completely power small electronic devices and even supplement larger ones.

Concepts:

Link: New Fabric Generates Electricity Via Your Body Heat – Mashable