This photo is intentionally large.  I think it's one of the coolest pictures I've ever taken.  
A thunderstorm rolled in as the sun was setting, and the light coming down was positively GREEN.  I ran upstairs to get my camera, hoping to capture the phenomenon.  I came down, opened the screen door and took a picture of the back yard without realizing that my flash was still on.  You can see the effect, below.  At first, I thought water had gotten onto the lens, but that's not it.  What you're seeing is the rain itself, as it falls.  I don't think I could have gotten a picture like that again if I tried.  The conditions had to be just right.
I especially like the big drop on the right that can be seen through.