Obviously of President Bush, I found this while looking at the Washington Post Online. The key is from the right of the image, thus the fill is from the left of the image. It is either ambient from the sun, or stage lighting from his speech.
This is of me, in Rome, drinking a Coke. There was enough ambient from the sun coming into the restaurant for the image to truly turn out. The key is from the back, the fill is from the front.
I'm a cat person, thus this image. The key is from the right and the fill, either ambient or another source, is from the left.
Obviously of Senator John Kerry. Equal opportunity for all first party cantidates. This isn't the place to show my political alignments. If you look carefuly at Kerry's right eye, you will see a shadow caused by his hand, thus the key is from the left of the image. And the fill from the right of the image.

While there is a strong key light in this image, if you pay close attention, you will notice some fill light bouncing off the walls of the room and entering from the other rooms.