Attached Link: click here

I was thinking along the same lines as scanmead.  Years ago there was a grey scale chart in the tutorials here that you could use for setting brightness and contrast.  It seems to  be gone now.  Once I started getting more involve in photography I bought a monitor calibration device. 

The attached link is a simple brightness/contrast calibration scale.

http://displaycalibration.com/brightness_contrast.html