A seemingly crazy idea  from the Keck Institute for Space Studies in California may in fact be just crazy enough to work (cue dramatic music!).
The Keck institute imagines a long-distance craft rocketed into space using existing technology. The probe would propel itself slowly to a small target asteroid (only around 20 feet across) over several years, using exotic engine tech like solar ion drives. When it got there, it would study the rock, snag it in a bag-like trap measuring 30 feet by 45 feet, then slowly shunt back toward the Moon, where it would drop it in orbit. The whole thing could cost about the same as the Mars Curiosity  probe and be over by the 2020s.
Bonkers as this plan sounds, the resultant nearby asteroid could be an important proving ground for all sorts of tech. Future private asteroid mining companies , and scientific groups, could study an asteroid up close without the cash and complexity of zooming far out to the asteroid belt. Ambitious companies like SpaceX  could study the rock and propose technology to protect Earth from any future planet-smashing  asteroid encounters. And the entire mission is so wonderfully quixotic it could spur  widespread tech innovation and educational enthusiasm for math and science back home.
For the benefit of humankind (and potentially booming businesses), would you prefer we send humans back to the Moon, or try something as novel as creating a moon for the Moon?
[Image: Flickr user FlyingSinger ]