Why should you spend $400-$1000 on a skylight and ruin your perfectly good ceiling when you can have one of these.
The problem with most windows is not that they don't let light in... it's that the light falls on the floor instead of filling the room. The problem with a skylight (as lovely as they are) is that they cost $400-$1000 and will take up more than one weekend with the necessary destruction of some portion of your ceiling.
Solution: add a mirror (or two) to the window sill and angle it into the room.
The mirrors cost about $7 at your local hardware store and when angled properly will redirect sunlight off your face or desk, and onto the ceiling where it provides free natural light for the whole room.
Why pay for electricity and expensive "natural" light bulbs when you can have actual real sunlight?