I've seen a lot of requests for heterochromia, which I think would be quite cool, but genetically inherited heterochromia is only know to be caused by Horner syndrome, Waardenburg syndrome and leucism. I'm not sure what the first 2 are, but leucism is a genetic trait which causes partial but not complete loss of pigment. We already have albinism and melanism, so this gene would be pretty cool to add too Leucistic animals are often mistaken for albinos. Although both have white fur and pink