melonDS - A Nintendo DS emulator with support for commercial games.
RetroArch - RetroArch is a frontend for emulators, game engines and media players.
mGBA - mGBA is an open source emulator of the Game Boy Advance. The goals are speed and accuracy.
nds4droid - nds4droid is a free, open source Nintendo DS emulator written for Android smartphones.
DeSmuME - DeSmuME is a freeware emulator for the NDS roms & Nintendo DS Lite games created by YopYop156.
gpSPhone - gpSPhone is a Nintendo Gameboy Advance emulator for the iPhone and iPod Touch.