Came here to post this, but CrossEyed7 did a much better job than I had planned.
I'm really busy right now, but plan to get Crosswords Plus, Professor Layton and the Miracle Mask, and Paper Mario Sticker Star eventually.
I got NSMB2 as a download and keep Mairo 3D Land in the cart slot. This has been a happy arrangement so I can easily see the advantage of having DLC for portable gaming. My wife is having back surgery soon so I've been in and out of the ER, doctors offices, pharmacy, etc. while towing my six-year-old and my DLC on the 3DS has been a welcome distraction for her without the fear of losing a cart. (I recently found a LeapPad cart in the couch and a DS cart in between the car seats. Over the summer my father mailed me some DS stuff that was lost last Xmas.)