I might get banned for this, but look for a repo called iPhone Roms. I'ts got everything you need.
You didn't hear from me... (I've always wanted to say that
)
In case you decide not to, they go in the following:
GBA - /var/mobile/Media/ROMs/GBA
Genisis - /var/mobile/Media/ROMs/GENISIS
NES - /var/mobile/Media/ROMs/NES
SNES - /var/mobile/Media/ROMs/SNES