Oh man, where to start?!
There are SO many amazing Super Famicom games that weren't released in the US. I'll list the ones I have:
1ST PARTY NINTENDO GAMES:
-Mario's Super Picross - Color sequel to the original Picross games on Gameboy!
-Mario & Wario - A puzzle game that uses the SNES mouse.
-Wrecking Crew '98 - Remake of the original (also includes the NES game)
-Kirby KiraKira Kids - Japan-only Kirby puzzle game! It's the same as Kirby Star Stacker on Gameboy.
-Sutte Hakkun - Puzzle game featuring a drinking bird.
-Power Soukoban - AWESOME Zelda/Boxxle Mash-up with awesome music/graphics. HIGHLY recommended!!!
-Marvelous: Another Treasure Island - Fun adventure game made by the Zelda:LTTP team!
SQUARE/ENIX:
-Nangoku Shonen Papuwa-Kun - Fun 2D Platformer based on a manga/anime series.
-Star Ocean - The 2nd game in the series! Recently released in America on PSP.
-Treasure Hunter G - Squaresoft's last big RPG on Super Famicom.
-Hamelin No Violin Hiki - Awesome 2D Platformer from ENIX based on a classic manga/anime series.
OTHER 3RD PARTY GAMES:
-Go Go Ackman 1-3 - Fun 2D Platformers with character designs by Akira Toriyama! (DBZ/Dragon Quest)
-Super Soukouban - Boxxle for Super Famicom!
-Umihara Kawase - Fun 2D Bionic-Commando-esque platformer
-The Firemen - Awesome 2D Firemen-action game!
-R2: Rendering Ranger - AMAZING 2D Shooter/action game from Virgin. Looks like a PS1/Saturn game!
-Super Back to The Future 2 - Ridiculous yet fun 2D platformer
-Flying Hero - Funtastic Vertical Shooter
-SD F1 Grand Prix - Mario Kart clone that's actually quite fun!
-Gon - 2D platformer based on the manga character! Some of you may know Gon from Tekken 3.
-Gunman's Proof - Zelda-like action-RPG set in the Wild West.
-Ghost Sweeper Mikami - Crazy 2D action game based on the anime.
-Godzilla: Kaijuu Daikessen - Pretty awesome Godzilla 2D Fighter!
-Rockman & Forte - AKA: Mega Man & Bass, this was only released on GBA in the US. This was considered Mega Man 9 until the real deal came out last year. Personally my favorite Mega Man game.
I have all of these games so if you have any questions let me know!