The MagicKey 3 (MK3) by NeoFlash Team s a development tool for Nintendo DS. Instead of relying on cartridges like the Neo Flash 512, it uses the memory from an SD or MMC card (not included) that you plug in through the MK3 adapter. Because of the cheap price of SD and MMC memory, and the large capacity available (up 32GB!) the possibilities are endles!
This MK3 version includes 256M of flash mem on board for extra features.