Power cable bags are good for random cables in your go-bag. (Cisco console cable, micro-USB, power cable for my laptop charger.)
Not good for hand-embroidery, as the weave is very very fine and you're going to drive yourself nuts trying to cover any amount of surface. It's also very firm and you will stab yourself due to needing a sharp needle and forgetting your thimble. I did try though. I wanted to label with pretty colors vs. bad sharpie handwriting.
I suspect they'd take ink stamping very well, so long as you put something absorbent in the bag to prevent bleed-through.
Stacking cable bags hold small knitting projects. I've thought about using one to hold my common screwdrivers, with a couple of paperclips slipped through a few warp threads.
Power-injector bags are good for dice bags.
Who's guessed I work for a VAR and have a heap of these things?