Yesterday I had lunch at a co-worker's house, where I met her three Main Coon cats. One of them had splendid polydactyl feet:
Some people think Maine Coons are kind of supposed to be polydactyl. A high percentage of the breed does tend to be. That may possibly be because Puritan settlers brought them on board ship and settled in Yarmouth, MA and Halifax, Nova Scotia. Neither of which is Maine, I know, but it IS conveniently located in between there. Here's a great article on Maine Coons.