Peter Bellamy sang a song about Nostradamus, as written by Al Stewart.

As for Traditional, let's take a leaf out of the 1954 Definition shall we? The term can [...] be applied to music which has originated with an individual composer and has subsequently been absorbed into the unwritten living tradition of a community.

Once we've crossed out unwritten (which barely qualifies as a qualificiation in terms of actual folklore these days) I would think that just about covers just about everything.