How about Ceres as a giant radio telescope:

http://www.opennasa.com/2009/03/08/the-benac-orbit-keplers-follow-on/

The Benac Orbit, Kepler’s Follow On

Once Kepler finds the other Earths, it time to listen to their radio stations!

So here is the next big thing: Craters as huge satellite dishes for antenna feeds orbiting above them.

Think Arecibo, but a bagillion times bigger, and instead of that little white thing hanging on cables with winches you have a satellite flying above the dish.

Ceres, you big ball of radio wave reflective ice and rock, this is what you–and your equatorial craters–were made for! Orbital parameters copy write. (But if you must know: http://www.twitter.com/johnbenac)