These are remixes and/or covers of Cave Story's music.

[REMIX] On To Grasstown by FOAW (Functional on a Whim)
Balcony (Original Mix) by Kill The Upstart
Cave Story by Careless Juja
The Journey Goes On by Wedge of Cheese
The Angels of Hell by Random Hero
Doukutsu - Last World v1 by Rebekah Moss / Lillian Poolan
Moonsong by Thomas Kern
Cave Story Theme by Koolfox
Zona Desértica REMIX by Fernando Calvo

Sheet Music
Cave Story songs reproduced with, or for, real instruments.

Two piano Cave Story medley by wedge of cheese

These are various tracks (not necessarily related to Cave Story) built with one of Pixel's music formats.

Doomsday Valley by Holden Oney
Ristar 4-2 - On Parade by Gugu-Ex (pxtone)
Mad World by Jo Arbeiten
MM2 Boss by Zerukin
Adventure by brianbdm
Brinstar by Jackalope
Kraid by Jackalope
Norfair by Jackalope
ISO 9000 by Jackalope
Lorenzen's Soil by Jackalope
Endless by GIRakaCHEEZER
Forest Temple by GIRakaCHEEZER
Gold Saucer by GIRakaCHEEZER
Ideal by GIRakaCHEEZER
Ion Divvy by GIRakaCHEEZER
Kraid's Theme by GIRakaCHEEZER
Miracle-matter by GIRakaCHEEZER
Never Die Remake by GIRakaCHEEZER
Ninja Fox by GIRakaCHEEZER
Pachu by GIRakaCHEEZER
Perfecta by GIRakaCHEEZER
Pink Gabriel by GIRakaCHEEZER
Putrid 2 by GIRakaCHEEZER
Puzzle by GIRakaCHEEZER
Pwntendo by GIRakaCHEEZER
Rainbow Resort by GIRakaCHEEZER
Reactor by GIRakaCHEEZER
Sunset 3 by GIRakaCHEEZER
UN Owen Was Her by GIRakaCHEEZER
m3m by BurnedKirby
vgsnippet by Roj
Techno Rush by Beasty
Speed by Beasty
Aztec Travels by Beasty
Gental Abyss by Beasty
Rush by Beasty
Dragon Castle by Fluff8836
High Temper by Fluff8836
Awexome by S. P. Gardebiter
Battle In The Dungeon by S. P. Gardebiter
Buriki by S. P. Gardebiter
Buriki Drumz by S. P. Gardebiter
Castle by S. P. Gardebiter
Chemical Plant Remix by S. P. Gardebiter
Draven by S. P. Gardebiter
FFL3 Tylon Machine by S. P. Gardebiter
Final Utopia by S. P. Gardebiter
Final Utopia Alpha by S. P. Gardebiter
Final Utopia Beta by S. P. Gardebiter
Green Hill Zone by S. P. Gardebiter
Hidden Palace by S. P. Gardebiter
Labyrinth by S. P. Gardebiter
Pain by S. P. Gardebiter (pxtone)
Pipe Dreams A by S. P. Gardebiter
Quake by S. P. Gardebiter
Tempest by S. P. Gardebiter
Tempest Looped by S. P. Gardebiter
The Warrior Inside Alpha by S. P. Gardebiter
Tile44 by S. P. Gardebiter (pxtone)
Weapon Select (Extended) by S. P. Gardebiter (pxtone)
Weapon Select by S. P. Gardebiter (pxtone)
WTSS Alpha by S. P. Gardebiter
Yehat by S. P. Gardebiter
Action by Wedge of Cheese (pxtone)
Battle by Wedge of Cheese (pxtone)
Cool by Wedge of Cheese (pxtone)
Crazy Action by Wedge of Cheese (pxtone)
Dragon by Wedge of Cheese
Dragzelire Fist by Wedge of Cheese
Dragzeloid's Kitchen by Wedge of Cheese
Elemenion by Wedge of Cheese
Epic by Wedge of Cheese (pxtone)
Final Boss by Wedge of Cheese
Forest by Wedge of Cheese
Golem by Wedge of Cheese
Grassland by Wedge of Cheese
Intro by Wedge of Cheese (pxtone)
Mission by Wedge of Cheese (pxtone)
Mortanro by Wedge of Cheese
Mystic by Wedge of Cheese (pxtone)
Prologue by Wedge of Cheese
Quest by Wedge of Cheese
Test by Wedge of Cheese (pxtone)
Titan of Thunder by Wedge of Cheese
Title Screen by Wedge of Cheese
Tundra by Wedge of Cheese
Voyage by Wedge of Cheese (pxtone)

Batch Download (ORG/pxTone)

Christmas Orgs by Wedge of Cheese