Here's my list of games I intend to add on my Mini:
Actraiser
Castlevania Dracula X
Chrono Trigger
Famicom Detective Club II (Jp w/ English Patch)
Final Fantasy - Mystic Quest
Final Fantasy II
Final Fantasy IV (Jp w/ English Patch)
Final Fantasy V (Jp w/ English Patch)
Final Fantasy VI (Jp w/ English Patch)
Ganpuru - Gunman's Proof (Jp w/ English Patch)
Hourai Gakuen no Bouken (Jp w/ English Patch)
Illusion of Gaia
Live a Live (Jp w/ English Patch)
Marvelous (Jp w/ English Patch)
Ogre Battle
Picross NP Vol. 1-8 (Jp)
Pilotwings
Rudra no Hihou (Jp w/ English Patch)
Sanrio World Smashball (Jp)
Seiken Densetsu 3 (Jp w/ English Patch)
Shin Nekketsu Kouha - Kunio-tachi no Banka (Jp w/ English Patch) [Precursor to River City Ransom]
Shodai Nekketsu Kouha Kunio-kun (Jp w/ English Patch) [Sequel to River City Ransom]
Soul Blazer
Super Mario All-Stars
Super Tetris 3 (Jp)
Tactics Ogre (Jp w/ English Patch)
Terranigma (PAL)
Tetris & Dr. Mario
Tetris 2
Tetris Battle Gaiden (Jp)
The Legend of the Mystical Ninja
Uniracers
Wild Guns
Wonder Project J (Jp w/ English Patch)
Wrecking Crew '98 (Jp w/ English Patch)
Zombies Ate My Neighbors
Plus, such rom hacks, if they work...
Mario Kart R
Super Metroid Redesign Axiel Edition
Oh no! More Zombies Ate My Neighbors
The Legend of Zelda Parallel Worlds Remodel
Super Boss Gaiden
Some Japanese games suggestions came from the other thread about exclusive games that never made it to western audiences.
http://www.neogaf.com/forum/showthread.php?t=1441427