Not exactly for metal. Christmas is coming along and its time to grind pounds and pounds of poppy seeds. (Iggy probably knows what this is about).
Use to take about 3 hours by hand and using the lathe certainly justified its purchase to my lovely wife.
I remove the handle of the hand grinder and chuck the whole assembly (chuck the end of the shaft) in the lather. The grinder is big enough that it hangs down vertically between the ways which keeps it from rotating. I place a large steel bowl on the ways, dial in for about 200 rpm and pour the seeds into the small hopper. About a 10-15 minute task which finishes with me saying "Aren't you glad we have a lathe"?
Other uses: I purchase one of those manual counters ($4± harbor freight) and taped it to my ways to be tripped by the chuck as it spins around. Great for rewinding coils as they go bad in my pinball machines. Fortunately most of the coils have the number of turns printed thereon so it becomes a no brainer operation.
Put 2 or three copper wires in the chuck and use the lathe to twist ornamental wire. After the braid (twist) they can be bent by hand to make holders for decorative plates or nick-knacks. The same twisted (or hand braided) copper wires can be hammered flat and is a good project for 5-10 year olds to make bracelets or rings.