Careful man, openly asking for links to do with emulation / roms could get you and the site in trouble.
There've been PC emulators for the DS for years now. At least three, since I remember using one to grab screencaps off of TWEWY. I don't like using them, though, since all the buttons on a DS seem like they'd be really awkward when mapped to a keyboard. I've owned three flashcarts, though. Maybe 4, but I've given two away. My R4 got lost for a while and I replaced it with a Supercard Two which I still use today. I love it to pieces and even when I buy games, I often end up using the flash cart anyway because of the convenience of carrying multiple games at once and being able to use save states. Apparently this one also works on the 3DS (just not for 3DS ROMs) so if I ever upgrade, I probably won't have to worry about it being obsolete.
I really wish I had an R4/Flashcard thingie to play DS Roms on my DS. I'd never have to buy another game for it :/ If I recall correctly, though, it's illegal to bring them in to the country or something.. Although, a friend mentioned you can actually get them here no problem, so I'll have to see. Yeah, that's not what he was talking about here, but a good DS emulator is DeSmuME, which can be found easily through google. ROMs are a touchier topic, but again, Google is your friend.
