I recently heard that there was a sci-fi related music form called "Filk."
What is Filk? Where can I find out about it?
Filk is music written and/or performed by SF fans, often on subjects related to SF or SF fandom. The term derives from a typo (for "folk music") in an SF convention programme book, back in the 1950s.
There's a pretty good introductory article here.
You can find it by following other links on the website referenced above.
To add to the previous answer, filk songs are often parodies of existing songs or take the music to a known folk song and write new, usually humorous lyrics to it. Since filking is often an informal event where everyone joins in the singing, using familiar music helps those participating get the song right, even if it is their first time singing the words. The songs are often fantasy or science fiction based, but not always.