Music Disc

Music Discs (aka Records) are only found in Alpha, and can be played in Jukeboxes. They play music made by C418. It has been stated that in future, there will be 14 music discs to find in Minecraft.

Gold Disc
The gold disc plays the track "13".
 * An ambient track consisting mostly of bells, such as those found in Japanese shrines.

Green Disc
The green disc plays the track "Cat".
 * An upbeat synth melody.

Acquiring Discs
Music Discs are dropped by Creepers when killed by Skeleton arrows. This can be achieved by getting a Creeper in between a Skeleton and yourself, and having the skeleton fire on you. Shooting the Creeper with arrows four times, or hitting it with an iron sword two times, will make this  method easier, as the Skeleton will only have to shoot the Creeper once. They can also sometimes be found in chests in dungeons.