My wife's friend has a pair of cats that each have 7 digits on the front paws. The extra two are in a thumb position. Aside from making the paws freakishly huge, they seem to be somewhat useful for letting Buddy and Overhill pry the lid off the bucket their food is kept in. It's a pity that they're fixed; cat evolution could have been on the fast track...

Note: I'm aware that the possession of extra toes is supposed to be non-hereditary. I'm also aware that Buddy and Overhill were both fathered by Kingfish, and he also had 7 toes on each front paw. *shrug*