I used to have that problem, losing screws in odd places. So I built a 120V, 15A superconducting electromagnet. Hasn't failed to retrieve a screw yet, but you better not be wearing a watch or have any metal fillings when you switch it on. Oh, and you have only a few seconds to use it before it warms up and you have to put it back into the liquid N2.

Of course, the last time I used it to fish a screw out of my PC's case.. Well, let's not go into that.