The history of the fountain of youth starts somewhere before Ponce de Leon and has ended up somehow to a water fountain in Florida. National Geographic tells a fascinating tale of how though one water fountain in Florida is radioactive, it may actually be extending the life of its drinkers.
If you think your gear runs out of juice at inopportune moments, consider the infantrymen of the world, whose lives depend on their gadgets maintaining a charge. Thus the MetalCell, a magnesium-based battery that charges with salt water. Or urine.