I can't believe I didn't know about this app until now! I've been using Brightness Control and I gotta say, Shades is much better. It maintains your contrast level. Why BC can't do this I have no idea, but BC gets all hazy as you dim with it. Shades also has a handy menu-bar control which is much better than BC's window you have to minimize, or hide the app altogether... lame lame lame!! Shades is the only game in town.