If you're like me, you tend to be disorganized while working, and quite a few times I've lost the chuck key to the drill press or lathe while working. I tend to set it down wherever, and "wherever" could be anywhere from the finishing bench to my pocket.
To solve that problem, I stuck a neodymium magnet (aka rare earth magnet) on the side of the drill press, and I keep the chuck key stuck there when it's not in my hand. Same thing for the lathe, I put one of the magnets on the headstock, and the key stays there when I'm not opening or closing the chuck.
Hopefully this saves someone else some time as well.