These music packages can be used to replace Spelunky's soundtrack. Just copy the files over the ones in the 'sound' folder and the game will play them instead.
Banjo-Tooie
Bomberman 64: The Second Attack!
Castle Crashers
Cave Story
Chrono Trigger
Eversion
Faxanadu
Hero Core
Kirby 64: The Crystal Shards
Paper Mario
Sonic the Hedgehog 2
Spelunky
Super Mario RPG: Legend of the Seven Stars
Banjo-Tooie
Bomberman 64: The Second Attack!
Castle Crashers
Cave Story
Chrono Trigger
Eversion
Faxanadu
Hero Core
Kirby 64: The Crystal Shards
Paper Mario
Sonic the Hedgehog 2
Spelunky
Super Mario RPG: Legend of the Seven Stars