You could build a planet-sized interferometric array without having to obtain land in different countries. If the orbit's much bigger than the planet, you can have most of the antennae always be usable instead of half on the wrong side. You can pick up wavelengths blocked by the atmosphere. You can build multi-kilometer single dishes out of mylar or steel cable, without gravity and air currents bending them. You can use it to focus sunlight onto surface locations, but probably shouldn't.