emu.kulichki.net/pristavka/en this site has several emulators and games, though not too much on the "complete" side, it's got a lot of what it does have
I used it to rebuild my lost NeoGeo collection
the best part is the main site is in russian, and the descriptions of the games on the english mirror look a LOT like they were run thru a web translator
well that might not be the best part for those who still need the roms, but it's the best part if you already don't care if the description helps at all...pcengine links seem to be broken, though
also don't forget that the vault at
http://www.classicgaming.com still has a lot of stuff