Only in Australia! There is a line of green egg laying NNs with rose combs. He states that the same genes that control the rose combs also control the green eggs. Must be true cause I have an older rose combed NN hen that started laying green eggs this year after laying brown for the last four!
http://www.geocities.com/Petsburgh/6624/index.html
http://www.geocities.com/Petsburgh/6624/index.html