So, after months of not using it, I decided to finally buy a replacement charger for my 3DS. I don't have any games (just Ocarina of Time 3D, which I had already beat before losing my charger) so I didn't see the need before. Sometime between that hiatus, an app was added. "Swapnote".
A little bit of context, one of the main entertainment features Nintendo added to the 3DS to make it sell is "StreetPass™" technology. 3Ds all have a wireless band radio of communicating short range with each other, mainly for multiplier games. Nintendo has always had a lot of cool applications for this technology, for instance "DS Download play" which allows two people to play the same game even if one person doesn't have it by temporary downloading necessary game files to play on the DS without the game.
The 3DS takes this further because "SpotPass™" is an always on (as long as the 3DS is on) and sends certain data to every 3DS that yours passes. Before, I thought this was just for the stupid built in game that made every person you pass with a 3DS join your 'army' or for 'meeting them' by meeting their avatar that they create, again for every person you pass.
"Swapnote™" lets you write or draw a message that gets passed to every 3DS you pass, which I think is much more using the potential of "SpotPass™".
Sadly, it sounds an awfully lot like tin-can.
EDIT: So, this apparently this application, while using "SpotPass™" features, only lets you send to people on your friends list. Every time you pass them. However, I bet it'll only be a while before Nintendo realized the potential of a message that sends to everyone.