Utility to make laptop display darker?

There are times when I'd like to dim my laptop display more than is possible with my system's current capability. For example if I'm downloading or defragging and I want to be able to turn down the brightness as low as possible but still be able to see the screen.

On my system with Vista I can use FN+F6 to turn it down but it could still go down further if I had a utility to make it do so. I can change the Power Options but that makes it permanent until I go back and change it again. I'd like to be able to do it on the fly. Anyone know of such a thing?

Thank you.

 

normally that can be done from within the driver utility from you gpu. what type of gpu is it? you should be able to go to the color controls and turn down the brightness and or contrast etc.. while its not the best option it will work