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.