Ok... "useful work application" what about some type of all-purpose programmable tester? This is something that's been on my to-do list for years.
Basically it's a little box with lights/LCD display etc and some test leads. Then you program it by switches/knobs or by menu to test a specific thing, in a specific range.
It's for production runs, like when you are making a batch of units (or testing resistors as JimB suggested) you program in the parameters and it gives a nice quick low/good/high indication, even with a added beep if you like so you don't have to turn your head to look at it.
There's nothing more annoying than having to test 100 PCBs for "make sure the voltage on IC2 pin 26 is >4.2v when you press button 3..."