Recapturing Waste Heat

This is an area with a lot of promise. Many attempts have been made to harness the energy content of waste heat. Thus far success has been limited (basically heaters and "grill-while-you-drive" devices). But with increased interest in energy efficiency we'll see more developments in this area, particularly with various energy media. Steam power may yet find new life in mobility. Here's an interesting concept:

http://www.autobloggreen.com/2008/09/05/clean-power-technologies-still-working-on-new-steam-assisted-car/