A while back, I thought about using solar collectors on the moon as a green energy source of unprecedented proportions. See, Earth is not good for solar collectors; we have all kinds of cloud cover and weather erosion; and our land space is extremely valuable. Contrast that to the moon; there is no cloud cover, minimal space weather erosion, and uninhabitable land.
The main idea is to manufacture solar panels on the moon using the local materials available, and then to send energy back to earth via laser.
This would require sending the moon a unit that could mine and process the appropriate materials, manufacture them, lay out the solar panels, and replicate itself.
Turns out, someone already has developed this idea fairly extensively (and I took the picture from their website):
http://www.shimz.co.jp/english/theme/dream/lunaring.html
