Over the years I have heard it both ways, some people like the black background with greyish writing and others like the traditional white background with black letters. I'm not necessarily going to switch (unless the response is overwhelming) but I want to provide the best experience possible for everyone.
When I first started the site I choose a black background for several reasons, one being that I wanted people to notice from the first second they loaded the page that this site was different than other sites, different than drudge, cnn, abc, fox etc. So to me a black background accomplishes that goal. I also think it looks better, and I think it's easier to read in a darker environment.
So let me know what you think have a vote and leave a comment. It gets lonely not knowing if anyone is reading what you write.
