What it is: A window installed in the ceiling. Some (called roof windows) are fixed; others open for ventilation.
Pro: Some come with remote-control blinds and coated glass that minimizes exposure to UV rays. If you have an attic, you can get sunlight into a dark closet or room via a tunnel-like skylight that runs to the space from the roof.
Con: You’ll have to climb onto the roof to clean the exterior.
Cost: About $150 to $1,500.