Credit to daniboy for this gem:
He recently showed me a program called f.lux.
It works by automatically adjusting the the brightness and contrast of your monitor as the day progress.
Just input your location (latitude/longitude) and the type of lighting you have.
Thus your screen is its usual bluish bright self (like the sun, they say) during the day and it takes on a reddish hue at night. You will love it best when you get up sometime in the middle of the night to use the computer.
In the case of my laptop, the screen colour temp is 6500K by day and 3400K by night. It is customizable.
Your monitor is a lot easier to look at at night and it works seamlessly no matter what program you're using. (You'd want to take it off if you're into professional colour work though.)
I say give it a try. It's free:
http://www.stereopsis.com/flux/Tell me what you think.