I have seen serious proposals for huge ion wind lifters that would station themselves at high altitudes to be used as permanent radio relays. I think they were powered by a microwave beam from the ground.

Not sure how well a radio relay would work when one is pumping high-energy microwaves at it all the time.

Another bit on the idea can be found here.

I personally think that if a sufficiently powerful and light energy source could be developed (probably nuclear), there might be some potential for developing a self-contained electrostatic propulsion system for atmospheric vehicles, especially if one could use other aerodynamic effects to enhance it.