A dark metallic blue case with black or white accents would be fantastic.
Dark metallic blue with some nice orange accents would also be pretty unique. The contrast between the cool and warm colors combined with some orange LEDs could turn out awesome.
I'd also like to see some white or orange LEDs being used in conjunction with any dark metallic colored case. Don't really see those but I can imagine it looking pretty sleek.
I would like to see one in British Racing Green.
Not that I am British or anything, I just really like the color even though I am from southern Illinois.