Updated: Now with alien abduction victim!
I took this photo of the school where I work, but the sky was really ugly and drab-looking. I set about trying to adjust the color and do all kinds of Jedi-Ninja tricks to make the actual sky prettier, but nothing looked believable. I finally decided to just replace the sky with sky from another photo, which worked beautifully. Then a student suggested putting something really crazy in the sky, like a scene from a space invasion movie, and voila! Although, I doubt they'll want to use this version for the webpage. They'll probably want something more like this.
The original picture is here.