My favorite (mis)use of Dosbox was using it to drive Symate for PLC programming. That let me switch to using a Linux netbook instead of dragging a laptop booted in DOS around a factory.
Same here, we had some buggy PLC controller software that would only run properly on increasingly hard-to-find old PCs, or more expensive embedded kits, due to timing issues. This was in an electroplating plant so they corroded to the point of needing replacement every year or so. Instead, with DOSBox set to an appropriate clock speed, we could use any commodity PC.
Did a similar thing with engraver software (which had a parallel port hardware serial key dongle that DOSBox allowed access to) and a dBASE IV program at a client's factory. Amazing piece of emulation that enables "ancient" code to run forever in small businesses around the world.
I used Dosbox to run a program to upload source code on old GE PLCs in order to covert to new systems. Couldn't have done it otherwise. Long live Dosbox!
My notes from the time: https://sites.google.com/site/waspvm/runningsymate374underdo...