I've often toyed with the idea of singing Bowie's "Please Mr Gravedigger" at a folk club, as it's unaccompanied on Bowie's recording. Would work quite well I reckon, if it's not too spooky, that is...

https://www.youtube.com/watch?v=wgLy2PAJRiQ

Some of those early Bowie recordings in the 60s, for Deram and the BBC, before he became properly famous, are a quite music-hall-ish and satirical and much more melodically simple than his later stuff. Songs like "Gospel according to Tony Day" or "Join the Gang" could be folked-up I reckon.