Composed of a light "aerogel" ribbon made mostly of carbon nanotubes, a new development in synthetic muscle systems weighs next to nothing, yet is stiffer than steel. Capable of operation in temperature ranging from -193 to 1,627 degrees Celsius, these carbon nanotube fibers can also expand by up to 200% through the application of high voltages, making them potentially useful in spacecraft components requiring high temperature tolerances. Of course, the voltages involved make it unlikely that these super-muscles will find their way into human prosthetics, despite the potential for applications in super-powered crime fighting.

Story at http://www.sciam.com/article.cfm?id=cnt-artificial-muscle
Abstract available at http://www.sciencemag.org/cgi/content/abstract/sci;323/5921/1575