I know this just from the artist/ color wheel perspective -- might not hold true for photos, though I'm not sure why it wouldn't.
Orange -- blue
pink -- dark green
violet -- yellowy-green
indigo -- orange
gray -- gray (darker gray -- lighter gray, lighter gray -- darker gray)
Not sure about tan and brown, as they're combinations of colors from the whole wheel. A light yellowy tan would probably be a dark purply brown -- something like that.
What are the opposites of black and white in RGB space?