I'd love to hear what you use them for!
Coiled storage of electrical extension cords. Just pull them out as needed, like twine from a twine ball, and neatly restow when finished.
I just got really tired of untangling the 100+ feet of connected cords every time we wanted to do yardwork with a weedwhacker, lawn mower, or reciprocating saw. It's especially embarrassing having poorly-coiled lines when you're a Navy family...