When Nintendo dropped the price of the 3DS mere months after its release in 2011, it offered a mollifying "Ambassador Program" to early adopters of the handheld system. That program included 20 free games available to players who bought the 3DS before a certain date.
The Nintendo 3DS Ambassador Program's second batch of games are now. You can see a full list here. Download them the same way you downloaded the NES games!
Back in July, Nintendo announced it was dropping the 3DS's price from US$250 to $170. To make it up to those who shelled out full price, Nintendo launched its 3DS "ambassador program",