US Department of Energy
U.s. Department of Energy: Fuel Cell Technologies Program: Fuel Cell Animation
A series of animated illustrations show how a polymer electrolyte membrane fuel cell works. PEM fuel cells are the most common type used in flex-fuel vehicles.
US Department of Energy
Fus Ed Web: Physics of a Fundamental Energy Source
An excellent resource on nuclear fusion! Using incredible graphics and excellent discussion, this site (with its several pages) provides an exhaustive online course on the topic. Click on the link for "a Guided Tour" and begin.