And yet, according to my wife's surgeon, gall bladder removal surgery is the most common surgery in America. (Though he might be biased.) You don't appear to need your appendix. You can live fine with one kidney, or half a liver. I think you can get by with one lung. I've had friends who've had huge portions of their digestive tract removed.

I realize that that just speaks to the body's generally robust build, and its redundancy, but you can probably remove more organs from a human body and have it keep running than random parts from under a car's hood.