Late Registration for Nintendo 3DS Ambassador Programme
Ok folks, if you still havn't got around to register for the ambassador programme and enjoy those 20 free games, don't lose hope.
You can also check your serial to see if its already activated.
The easiest way? scan the receipt, then either scan or take a picture of your 3ds serial, use image editor and merge both, optimize and save to .jpg or .png and make sure the size is not more than 1mb.