A little list of features request.
Add Default artwork when missing covers or fanart. A good theme for every platform when no fanart is asigned and a nocover asigned deault cover.
Autodownload suggested emulators and autoconfiguration at least of ALT+F4 hotkeys, every emulator has a .ini file and it´s easy to target and edit the hotkey to exit i think on mame that have esc by default or other like bluemsx. I know that is messy for all but at least a bunch of prefered emulators like retroarch and mame may be nice to autodownload and configurate the basics like controller(xbox 360 pad defaults). I know about another emulator launcher named emucenter2 that do this think.
A good parsing like the MAME adding in recent versions for thinks like DEMUL (NAOMI-ATOMISWAVE) It´s really a mess to make this games run because of the mandatory rom names and the naming on TheGameDatabase Like in MAME.
Funny achievements based on database data. Like DUNGEON rat when you run 20 rpg games or EASY TRIGGER when you play a lot on shooter games. Mushroom king when yout play a lot of nintendo games. Etc
Maintain all the image data mandatory with the same name that rom have. Is more easy to avoid duplicates and garbage. The images downloaded from thegamesdatabase or other added manually have nasty names with numbers of other things. emumovies not.
For submissions and moderation you can count me in too. I made a lot of contributions on other databases like gamefaqs,mobygames or the games database.