Entirely translucent, but with a coating to minimize scratching and hazing with use. A clear motherboard tray would be cool too... now, to find a clear DVD-ROM...
I'd like to see a gun metal grey with red accents. Also a white case with blue accents could be very clean looking. Load it up with some blue lights...
I would like to see a dark grey shade in matte, like a gun metal grey. This would still go well with DVD drives that have black face plates, and just be a welcome change from the black and white.
I've always preferred black cases myself, and these Enermax Ostrogs are beauties, even in other colors. Dark red or deep blue would catch my eye, I think.