Nikola Tesla had ideas about electrifying the Earth's atmosphere. That is, transforming the current to many millions of volts so that it could be conducted through air across whole continents. A few such power stations should then electrify the whole Earth, so that electrical machines could pick their energy literally from the air.
Keeping air on tiny worldsEdit
Asteroids, comets and other tiny worlds have very weak gravity. That makes them boring, airless worlds. But by conducting electricity through air, the air becomes an electrical conductor. Electrical conductors are affected by magnetic fields. If the tiny world is magnetized, this allows retaining of an atmosphere on it.
If the voltage gets high enough and the amps low enough, maybe even vacuum itself becomes an electric conductor? Apart from allowing cosmic-scale electrification, this also allows manipulation of space-time. Artificial gravity and antigravity, warp drives, wormholes, time travel... not even the sky is a limit!