melonDS - A Nintendo DS emulator with support for commercial games.
FCEUX - FCEUX is a Nintendo Entertainment System (NES), Famicom, and Famicom Disk System (FDS) emulator.
RetroArch - RetroArch is a frontend for emulators, game engines and media players.
Nestopia - A portable and cycle-accurate NES emulator written in C++
nds4droid - nds4droid is a free, open source Nintendo DS emulator written for Android smartphones.
gpSPhone - gpSPhone is a Nintendo Gameboy Advance emulator for the iPhone and iPod Touch.