Including the colour outside the primary content area wouldn't be very accurate, since this is dependent on the viewer's screen resolution. For example, viewing Facebook on a widescreen display yields significantly more white than on a non-widescreen display.

Design Tip: Never Use Black http://ianstormtaylor.com/design-tip-never-use-black/

I'm keeping white/black and greytones out for now. White/light greys are especially hard... how would you differentiate between the content and the background?

It's definitely on the list of things to address.