Maybe screw threader is the wrong term, but I just finished putting a trailer hitch onto my jeep, and with the hitch came these wire's which were wound like a coil at one end.
at first, I had no idea what they were for, and since I didnt think I would need to realy read the directions.....
anyway 1/2 way through and scratching my head trying to figure out how I was going to thread a bolt through the frame I figured it out...
basically they take a piece of maybe 20 g wire and coil it on one end. Then, you can thread the bolt end into the coil, then take the straight wire end and feed it into the frame of the vehicle, and out the hole you are trying to pull the bolt into.. finally once it's in place, just spin off the coil from the bolt and voala! its done easily and quickly! I'm sure that some of you have seen this before, but I havent, I am sure that we all can use something like this for 1000000's of hard to #$%#$%'ing reach places in our cars!
let me know if anyone wants a pic or if this doesnt make sence!