"Moonbow" by Garry Schlatter
One thing I learned many years ago from Tim Baskerville and Lance Keimig is that moonlight is almost identical to sunlight, except that it's not as bright (the moon is the same apparent size in the sky as the sun, and the moon's surface is nearly neutral gray, so the reflected moonlight is very similar in color temperature to daylight). So, if sunlight creates a rainbow immediately after a rainstorm, what happens when moonlight appears immediately after a rainstrom?
The answer is... moonlight creates a "moonbow" [wikipedia]. Basically, a moonbow is just a rainbow at night (yeah, I've never seen one either...).
Recently, Brisbane, Austrailia landscape photographer Garry Schlatter photographed a moonbow at 1AM one evening. You can read the entire story on his Flickr page.
Garry is also part of a great internet project called the Open Source Photo Guides. Garry has contributed numerous free online photo guides for Australia.