So today I was looking at the AndyMark site for their 500 key hubs, and I noticed a few parts of note:
Small Globe DD Hub - Finally, someone offers an easy, reliable way to interface with the Globe motor's double-D shaft! The bolt circle doesn't specifically match to anything I'm aware of, but you can fix that with a power drill. Color me tempted.
512 Key Hub - It looks like some 500 key hubs must've really been bored.
(Thank you, thank you, I'm here all week.)
375 Key Hub - Precisely what you think it is.
500/
375 Bearing Hub - If you can find a good use, they could be kinda nice. (I'm imagining a second stage of chain reduction, placed conveniently whereever you can drill a hole for a bolt to mount the hub on. I'm sure someone else has greater ideas.)
(And no, I have no ties to AndyMark beyond being a satisfied customer.)