Those newfangled synthetic wine corks make great blade covers for chisels and gouges. Colorful, too!
Use a breadboard to hold header pins straight while soldering. Insert the header pins into a breadboard and then align your circuit board on top, slot the pins through the PCB holes, and solder.
A washer with a pair of alligator clips (or small binder clips) make a pretty effective improvised workholding jig for soldering wires.
Frequent MAKE contributor Craig Smith made this ingenius puller by micro spot-welding together some nuts and bolts, to remove the gear from his cordless drill so he could replace the motor.
Use double-sided tape to secure tiny parts. You can also write the parts names, sizes, and other notes around the tape.
Chucky Lives!
Need to hold round stock for drilling or thread-cutting? Repurpose an old drill chuck as a vise.