Inspired by JThw8...
My own submission isn't all that great, but I know some others will be. I've got a flat screwdriver with a notch cut into the end for stretching out seat diaphragms and getting hog-rings where they need to go. Terrible tool--if you slip, you're going to get hurt, but it's always got the job done.
Many moons ago I was doing front wheel bearings on something or other and I destroyed the castle nut cotter pin. Didn't have a spare and was too lazy to go to the parts store or to go in the house and get a coat hanger, so I used an old cheapie mini screwdriver, stuck it in the cotter pin hole and bent it over a few degrees.
YaNi
New Reader
11/6/08 10:55 a.m.
Modified a small (slightly larger than pocket-size) flat blade screwdriver to easily remove the clips holding on the window cranks.
walterj
HalfDork
11/6/08 11:04 a.m.
Hitch pin for my lawn tractor
Brake adjustment tool for drums
Giant sail-cloth sewing needle
I've welded a few to rounded nuts to break them free
Magnetized for picking small items out of a tight spot
Drywall drill
Scribe for marking wood, copper and aluminium when no pencil is in reach
Used as a nail for hanging a large sign on the garage wall
Stud finder (see drywall drill)
mw
New Reader
11/6/08 12:03 p.m.
I use them most often to poke holes when looking at old rusty and rotting cars I am looking at buying. Unfortunately, I still always end up buying them.
I have one that my dad made with a couple odd bends in it and the tip ground to a point. The best cotter pin extractor I've ever used. Have broken one that I use on screw-type jack stands (like trailer stabilizers). Have also rounded & dulled the tips on big flat-tips for tire R&R on bikes (pedal & motor) and other smaller tires.