We have a few. My daughter's hamster is a "blue" which I believe is a combination of two recessive traits - black & opal. The male is a mottled which is a dominant trait. We had a litter of 7 (4 mottled & 3 normal) born on New Year's day. Of course, I was distracted by New Year's and didn't move Blueberry back to her own cage in time, so she had the babies inside the ball attached to the male's cage. LOL We kept one of the mottled boys and a normal girl (both het black & opal). I'd love to do some more breeding and recover the colors, but I think I've exhausted the friends that want hamsters list for now.

One interesting thing that I read: mottled is a lethal trait in the homozygous condition.