the flashcarts for the nintendo ds were the fucking shit, 200+ games on one cart and tons of homebrew to fuck around with. i had an mp3 player app that i used like a total dork looked like an ipod with the track information being on the top screen and an actual touch wheel on the lower screen. don't really see the reason for these things existing nowadays considering you can just buy an old switch and softmod it, but i guess if people can sell something they will