Here you can downlaod various apps & games for Windows.
An emulator for GBC and GBA, comes with numerous features that helps rom hackers too. Currently the best GBA emulator.
A gba emulator that also supports Nintendo DS games. Comes with Debugging feature.
A Nintendo DS emulator which can emulate most games. Runs smoothly and works really fast.
Bgb is a Gamboy emulator that can emulate .gb, .gbc and .sgb file. Works smoothly and runs almost all roms perfectly.
An open source emulator for Nintendo 3DS games, currently this is the only non-fake 3DS emulator.