Urm? http://www.asus.com/Motherboards/Intel_Socket_1155/SABERTOOTH_Z77/ Ta-da! About black: it's an overwhelming consumer demand. Black with Red or Blue. But yes, I agree, it's very boring seeing a whole market of black boards.
I wouldn't mind black with white trimmings, maybe suggest that to your engineers as a 'classy' or something series. I'm no good with making up names.
I'm talking not about a cover per-se but something that just gives the illusion of the PCB being white/orange/pink. You know? Still the saberthooth is awesome. I wouldn't mind black, but for the love of god add some green (XFX/EVGA) or some white for some cool contrast. I wouldn't mind orange either.
Cover it in a mirror finish, then light up your case (as shown above). The problem is covering the PCB is all the little components.