While blowing my nose repeatedly this morning due to this nasty cold, I thought about how nice it would be to have a redundant set of breathing passages that I could use when the usual airway is all stuffed up. Of course, there are plenty of other body parts that would be handy to have a spare set of. Extra arms or legs, for example, could really help you in a lot of situations. A spare heart could save your life. I think if I could have any extra body part, I would choose to have one extra arm.
What would you choose?