I hope you don't mind me saying this, but who is the site for?
I'm asking because while black is very popular, it isn't user friendly with everybody. For some it's highly unfriendly.
I am one of those unfortunates that suffer with something termed Lazy Eye. The eyes don't react as they should. Snow gives me blinding headaches if it were not for the type of glasses I wear.
Black - the pupils open out wide to let more light in. Then there is the text which wants to close the pupils because it's brighter than it's surroundings. Two minutes and the eyes start to stream and that's me spent for a while.
Curiously black being unfriendly gets a mention in a book on css I have, yet so many designers ignore it!
So what I am saying is that without realising it, all those that go with black are limiting the visitor or member potential - just as there are some that have to avoid certain displays of flash. If you want to maximise your sites potential, neutral colours that sit comfortably together are the best to go with.
Sorry if that's put a spanner in the works, but better it said at this early stage than after the design has been sorted. but there again..you can always ignore this if you want to.