Thanks to all of you who responded to the Commodore message; I’ve tried to read responses on this weblog, as well as those at dcemu. My original question was regarding the C64 and VIC-20 systems, but it seems like most of you would rather see an Amiga emulator than a C64/VIC-20 emulator.
I’ve also noticed interest in the Spectrum series (ZX-81 certainly hasn’t missed any opportunities to remind me of the need for such an emulator 
), so I’ll keep both of these in mind.
I am interested in finding out why those of you interested in these systems don’t use PSPUAE and PSPectrum, however.
I'm a programmer with too much interest in too many programming languages, and not enough time.