I really like the space fountain concept: it's utterly ridiculous, but completely feasible. It also doesn't need to be as big as a space elevator to be useful (a partial space elevator wouldn't work); space fountains can be as big or small as desired, and applications like radio towers have been mentioned.
It would be nice to see even a metre long demo, which I imagine might be possible as something like a student project (4 coil guns exchanging ball bearings).
It would be nice to see even a metre long demo, which I imagine might be possible as something like a student project (4 coil guns exchanging ball bearings).