It makes me incredibly sad that people are willing to stare straight ahead at a fucking lightbulb (a.k.a. sites with a white background) and destroy their vision.
Most probably is due to a non-optimal screen both at home and work-place, but I suffer from the same issue even on 2010 iMacs.
But the most pleasant scheme for me (I mean, my eyes) is light-gray-on-dark-gray.
In fact the W3C has a good calculator for colour contrast [1], which I think is a good guide for calculating colour contrast when designing sites
[0]http://ianstormtaylor.com/design-tip-never-use-black/ [1]http://www.w3.org/TR/WCAG20/#contrast-ratiodef
About eye stress.. that's another story. Could anyone here point us to a scientific paper out there?
Same reason AutoCAD is shown with a white background in publicity, but users switch to a dark background the instant they have to use it professionally.
Same thing with a text editor... Emacs default to white, but the first thing I do with a fresh install is to change it to a dark theme.
Also, see my reply to DustinCalim's comment.