If someone wants to take on a huge (but useful) job, It would be a great help to ethnomusicologists and scholars of folksong if a metrical listing were available for at least the traditional songs we know. Historically, many of the ballads were sung to melodies often associated with other ballads--with some, though, there were variants in meter---and the dates and sources for these variants can be a key element in tracing the ballad's history.

I've long been intrigues by how the "feel" of a song changes when you change the melody for one of the same meter: Try Clemintine to Deutschland Uber Alles, then to Babylon is Fallen, then to What a Friend We Have in Jesus and even to God Rest Ye, Merry Gentleman. To name but a few that fit.