Sources: http://kotaku.com/5835706/full-list-of-free-famicom-games-for-3ds-owners
and
http://www.officialnintendomagazine.co.uk/29941/more-3ds-ambassador-games-confirmed/
Here are the 10:
Super Mario Bros
DK Jr
Balloon Fight
Ice Climber
Legend of Zelda
Wrecking Crew
Mario Open Golf
Yoshi's Egg
Metroid
Zelda II
This just leaves 3 GBA games to be announced: I'm hoping for Minish Cap, an F-Zero and a Fire Emblem.