Yeah I got one a couple of christmas's ago so my daughter could play backed up versions of her bought games.
Ours was called a supercard, cost me about $110 from Ebay and consists of 2 gizmos that go into the 2 slots on the DS with a micro or mini sd card fitting into one of the gizmos.
Also comes with some easy to understand software.
Ive seen ds games illegally packaged on torrent sites, if anyone ever suggested using one of these gizmos for playing illegal copies of games such as those available on torrent sites I'd hugely discourage it.
The 'supercard' looked like this, the part that went in the other end was called a passkey or something similar.
