DeSmuME is a working Nintendo DS emulator emulator that can play DS homebrew nds roms. It can support homebrew nds rom demo programs and a handful of wire-less Multiboot nds roms. Some features of this DeSmuME download:
Emulates 2 CPUs
Direct DMA
Supports only Mode 0
Supports for sprites

Information
The Nintendo DS is a handheld game console developed and manufactured by Nintendo, which was released in 2004. The hardware features a clamshell design, with two LCD screens - one of which is a touch sensitive screen. The Nintendo DS also features a microphone and supports wireless IEEE 802.11 (WiFi) standards,[7] allowing players to interact with each other.