In September 2003, the European Space Agency (ESA) launched their SMART-1 probe to study the moon. After completing its mission, SMART-1 is nearly out of fuel, and scientists plan to send it off with a bang.
I would say "Literally," but given there's no sound in a vacuum, that wouldn't be entirely true.
However, if there were air on the Moon, there would definately be a bang because the ESA plans to end the probe's mission by slamming it into the Moon's surface.
The result may be visible from Earth with the use of small telescopes. Experts have predicted that the resulting fireball from the energy of impact and the leftover fuel could be as bright as 7th magnitude (the faintest magnitude visible to the unaided eye in completely dark skies). However, other estimates say it may be more than 8 magnitudes fainter being about more than 1600 times too faint to see without aid.
However, it will be an interesting target for amateur and professional astronomers alike.
For more information, check out Space.com's article.