I assume by "and can be controlled 100% by a controller" he wants to be able to switch between different emulators and load ROMs all from the controller?
In that case you're looking for a frontend for your emulators. I just found one called EMUlaunch, I tested it just to see if it works on PowerPC and indeed it does 🙂 Haven't tested it beyond that, so you'll have to play around with it, but it seems pretty cool. Here's the link.
As for actual emulators, Zophar.net was always my go-to spot, although I'm not sure how up to date it is thesedays.