Nintendo made everything live for the NES part of the 3DS Ambassador program, making 10 old school games, some of 'em genuine classics, available for free. Another set of Game Boy Advance games will arrive later on this year.
Downloading them is a huge pain in the buttox. Don't believe me? Here's a step-by-step process, taken from a 3DS.
Tap that eShop button.
Now, click the Menu button.
click on Settings / Other.
Click your downloads or Titles you've downloaded(for the EU folks) .
Then dowload you're games.