Don't know if this was done before (surley it was somewhere) but I found it rather annoying to change haircolors over and over again to find the best looking combination.
So I made a couple of screenshots for me (and you!) to see which haircolor will lead to which formcolor. Not much surprise here in most cases, but it might be nice to see for some people. Sadly, there are no different combinations of bear- and catforms as there are with (as I think) nightelf and tauren forms, where not every bearform leads to exactly the same catform.
Enjoy.
Black
Blue
Dark green
Grey
Light green
Orange
Pink (Nope, this is not an error!)
Red
White
Yellow