I'm curious. How would I go about running GBA and NDS homebrews, dev kits, and imports on my DS? What's the best hardware to use? I want to play Osu! Tatekae! Ouendan already... -_-
supercard + superpass = DS love
you can get SD or CF versions, depending on your flashcard preference.
try http://www.hopebuy.com to get 'em straight from the source, if the site isn't horribly broken again. if not try http://www.kicktrading.ca
If one exists, will these also allow running of SNES emulators and homebrew ROMs?
yes, the supercard runs homebrew stuff just fine.
as far as I know there's no SNES emulator for the DS, but when one is inevitably released it will almost certainly work with it. the supercard team might even incorporate it into the firmware like they did with pocketnes for the GBA.