I currently work at a game studio called Wahoo Studios. It's a beauty of a studio, small enough to be friendly, big enough to be stable.
Brent Fox, our Art Director, has challenged us, his faithful artists, to a new piece of art each month. I missed the Christmas card design, despite having a few ideas. January's art challenge was to do a study of light, seeing how varied light sources interact differently with a given surface.
He gave us a few character design sketches from our resident concept artist, Shawn Boyles. (We could do one of our own, but I wanted to see what I could do with one of the designs.) So, I took this sketch from Shawn:

And did this to it:

And this, to show what a different color of light would do. The colors of the character stay the same, it's just the light that changes.

I'll try to do this to one of my own projects here when I can carve out the time.