Filk
From AmtWiki
A filk is a fannish word that is starting to see real world use, the specific term refers to songs that 'borrow' the tune from another song. "The Twelve Rounds of Balrog" filked to the tune of "The Twelve Days of Christmas" is an example. Wikipedia definition
For Filks Written by Amtgarders Check ot the Amtgard Songs page.