I'm helping a magazine with a story of the early days of podcasting, and came across these two musical podcasts from May 2005.
The first is a duet with Amy Bellinger singing the theme song of Green Acres. She sang the Eva Gabor part and I did Eddie Albert's.
The second is a group sing of Dixie.
In both cases the recordings were created in a totally low tech way. Play the previous version on your sound system, record that and your vocal part and upload it. Next person does their part on a voluntary first-come-first-serve basis. No coordination, whatever happens happens. ;-)
We got up to five parts with Dixie.