My parents had some polydactyl cats once, after the half-wild mommy cat just turned up at our farmhouse one day. She had really weird feet with some tiny double-decker toes. It didn't seem like it bothered her too badly. Some of the kittens just got big feet with a few extra toes, and some were pretty much normal.
Had a white cat once with one extra inside toe on each paw. The claw on the extra toe would get caught in the carpet when she walked. Had different color eyes also.