A hand-cranked wool carder converted to bicycle power by Katharine Jolda. According to the video, she finds it more comfortable and efficient to operate the carder by turning pedals. Video is "Cyclocarder: Katharine Jolda" by Maker Faire, http://www.youtube.com/watch?v=RSmSVI87zI4.
There are table-top sized carders that can be hooked up to a motor run on solar power (or regular current for that matter) but this is a much more direct way to use alternative energy.
It's also a way to repurpose used equipment, such as bike frames, rather than cause the manufacture of new materials such as photovoltaic panels.
Must work very well for promotion and awareness-raising at public events: it's so eye-catching and unusual.
Jolda sells Cyclocarder™ plans and kits on the Fibershed marketplace website.