RetroArch

Summary
RetroArch is an open-source, multi-system emulator frontend available for many platforms. At the time of writing, the 3DS port of RetroArch emulator cores are rudimentary but are gaining a bit of polish in every update.

Ported 3DS Cores

 * 2048
 * CATSFC (SNES)
 * CATSFC PLUS (SNES)
 * FinalBurn Alpha CPS1 (Arcade/Console)
 * FinalBurn Alpha CPS2 (Arcade/Console)
 * FinalBurn Alpha NEO (Arcade/Console)
 * FCEUMM (NES)
 * Gambatte (GB/GBC)
 * Genesis Plus GX (SEGA 8/16-Bit consoles)
 * gpSP (Game Boy Advance)
 * Mednafen (Neo Geo Pocket)
 * Mednafen (PC-Engine/Turbografx-16)
 * Mednafen (Virtual Boy)
 * Mednafen (WonderSwan Color)
 * mGBA (Game Boy Advance)
 * Nestopia (NES)
 * NXEngine (Cave Story)
 * PCSX ReARMed (PS1)
 * PicoDrive (SEGA Genesis/CD/32X)
 * QuickNES (NES)
 * Snes9x Next (SNES)