What about novels, plays and films that are based directly on songs - and vice versa. I heard that Woody Guthrie composed "Tom Joad" after seeing the film based on the Steinbeck novel "Grapes of Wrath". And that the melodramatic ballad "Gill Morice", which is in the DT database, was staged as a play (I'd like more details).

I have more knowledge of songs in Irish and Scottish Gaelic: Ailein Duinn (in the DT) was the basis of a radio play and I think it was on the live stage also. A' Bhean Eudach (one women drowns another woman because of jealousy) and Caoinneadh Art Uí Laoghaire (widow's lament) inspired short films. An Mhaighdean Mhara was retold as a novelette by Cliodhna Cussen and is the subject of a play and arts exhibition to be staged this month by school children in Conamara.