Well, there's
Strings by Aurora, which offers their strings in black, hot pink, purple, orange, blue, gold, clear over metal (silver), green, and red. They list at about $35/4string set, but I picked up a set of 45-105 in orange for $21 + $2.07 ship on the Bay. Just search bass strings for keyword Aurora and several pop up from 3 or 4 eBay stores. Some have excellent prices, some charge more than list (duh).
Example.
I just ordered a set of hot pink strings for my black & silver G&L Legacy guitar from an eBay store, and what's really cool is that even the plain strings are anodized in the matching color. Hot pink should look really cool against black and silver swirl.
I have a red bass; I was thinking of stringing it green for Christmas, and I got the orange strings for my orange/ebony ASAT bass.
DR also offers coated strings in their Extra-Life series in several of the same colors as Aurora.
Just Strings stocks the DRs in black, red, pink, blue, and clear (silver). Although DR's website shows yet more colors, their catalog shows the same color selection as stocked by Just Strings.