First 3DS Flashcard !! Crown3DS [Video]
The Crown3DS, seemingly built over a commercial cartridge, is only able to play commercial 3DS games (one at a time) for the time being. Some sites are already taking preorders for this starting at $99. This only supports 1 game at the moment - the game shown in the video. They are working on dumping other games and enabling compatibility with all commercial games. They are trying to be extremely cautious as they are afraid their device might get plagiarized by other teams.
Official Site: Crown3DS Card Which Supports 3DS Games - crown3ds.com