Wikipedia
Libnds
libnds, formerly NDSLIB, is a library created by Michael Noland (joat) and Jason Rogers (dovoto) and is maintained and updated by Dave Murphy (WinterMute). It is meant to be an open source alternative to Nintendo's commercial SDK for the Nintendo DS handheld game console. It allows programmers that do not have access to the Nitro SDK to create Nintendo DS homebrew. Libnds supports nearly all features of the DS including touch screen, microphone, 3D hardware, 2D hardware, and IEEE 802.11b Wi-Fi via the dswifi library.