One more reason not to use a black background on a website or blog… Glare!
I have a new monitor, one that stretches wider than it is tall. It is also shiny for some reason. The one that came with this computer was not shiny but this one is. Anyway, I find websites and blogs which use a black (or very dark) background are pretty hard to read. I get glare which I have to bob my head around to try to read through. Most of the time I just end up skimming to see if I really want to try reading anything.
So, now you know. Black is not the best choice for a background colour, for yet another reason.