Wow, I cannot believe I have not touched this topic until now. 3DS is only 3 years old but it has already amassed a massive RPG library. The DS was a fantastic system for RPG's, and 3DS feels cut from the same cloth.  I will try and sort the games as best I can, and if I miss anything, please, feel free to list them in the comment section below. 

Original Titles

Fire Emblem: Awakening (Developer: Intelligent Systems)

Bravely Default (Developer: Square Enix)

Pokemon X/Y (Developer: Game Freak)

Shin Megami Tensei IV (Developer: Atlus)

Mario & Luigi: Dream Team (Developer: Alphadream)

Rune Factory 4 (Developer: Neverland)

The Legend of Zelda: A Link to the Past (Developer: Nintendo)

Kingdom Hearts: Dream Drop Distance (Developer: Square Enix)

Etrian Odyssey IV: Legends of the Titan (Developer: Atlus)

Ported Titles

Shin Megami Tensei: Devil Summoner - Soul Hackers (Developer: Atlus)

Shin Megami Tensei: Devirvivor Overclocked (Developer: Atlus)

Tales of the Abyss (Developer - Namco)

Unlocalized Titles

Digimon World Re:Digitize Decode (Developer: Namco)

Dragon Quest VII: Eden no Senshitachi (Developer: Square Enix)

Dragon Quest Monsters: Terry no Wonderland 3D (Developer: Square Enix)

Dragon Quest Monsters 2: Iru to Ruka no Fushigi na Fushigi na Kagi (Developer: Square Enix)

Metal Max 4 (Developer: Kadokawa Shoten)

Upcoming Titles

Persona Q (Atlus)

Bravely Second (Square)

Kinki no Magna (Marvelous)

Pokemon Omega Ruby/ Alpha Sapphire (Nintendo)