Nintendo has recently announced, after the cut the price from $250 to $170, that if you registered on the 3DS E-Shop before August 12 you are eligible for the ambassador program automatically; otherwise follow the procedure to register, if you bought 3DS before Aug 12th. 

Go to this url :  Eligibility

Here is the youtube video I have made :

Free Games List 

Only five of the ten NES Virtual Console games have been announced so far. They are as follows:

• Super Mario Bros
• Donkey Kong Jr.
• Balloon Fight
• Ice Climber
• The Legend of Zelda

Only five of the ten GBA Virtual Console games have been announced so far. They are as follows:

• Yoshi's Island: Super Mario Advance 3
• Mario Kart: Super Circuit
• Metroid Fusion
• WarioWare, Inc.: Mega Microgame$
• Mario vs. Donkey Kong

Steps: 

• Click on “How To”
• Then “how to confirm you are eligibility
• Type in the serial number on the back of your 3DS

You will see your eligibility confirmation. 

Thanks,

Abhishek