Long time no see. Glad to see some familiar names here still.
I came across Big Mess o' Wires' "Wombat" USB to ADB converter.
I have a couple Griffin iMates, and made a couple ADB to USB adapters using Teensy microcontrollers for using the Extended Keyboard II on my PC, so I thought meh, yet another converter.
This one can go the other way, too: using a USB keyboard and mouse (and USB hub) on an ADB Macintosh.
I've tested it on my PowerMac 6100 with a Dell USB keyboard and Microsoft optical mouse. Both work a treat. Now I have to dig the LC II out of the crawl space...
I remember back when USB first came to the Mac, using USB input on an ADB Mac was one of those "impossible, will never happen" things.
Provides keyboard power-on using F13.
I have no affiliation with Big Mess O' Wires. This was an impulse buy, and for me this 'impossible' device was worth it (including the unexpected @#%&* $18 customs fee to cross our formerly open border).