My most obvious choice would be When All Men Sing.

There is this wonderful song by Graham Pratt (probably best known for "The Black Fox") The Minstrel about the different type of songs through history: War, Love, Bawdy, Protest, Industrial etc.

DonMeixner: - I'm not sure that "The Merryman and his Maid" (it's actually a duet with Elsie Maynard) is really about singing - it's a song about a rejected lover who wins his love in the end - which of course Point singularly fails to do in the opera. I must admit to having sung it several times in folk clubs though - as well as on stage.