Well, after an evening (looooong evening!) of accompanying the other singers on mandolin, harmonica, banjo, or guitar (whichever seemed appropriate to the song), I'd probably use my turn to sing one of my own songs. I just looked to see if "World of Time" is in the Digitrad, and it's not yet there (probably scheduled for MS-Digitrad 98 or some such product), so I'll point people to my web page: http://members.aol.com/rjclayton/ which has a dozen or so of my lyrics, for the words to the chorus (actually, it's easy enough to pick up that you don't have to go there to get the words, but you might just like something you find there anyway).
If I were restricted to traditional material, I suppose I might do my guitar arrangement of Stephen Foster's "Angelina Baker," or my setting of "Robin Hood and the Tanner."
Then I'd go back to providing another instrumental voice to the proceedings.