Generally what happens in a PermaThread, is that the "moderator" takes command of the first two or three messages in a thread, so the most pertinent information is at the top of the thread. Other people post information or comments, and the person in charge consolidates that information into the top messages and deletes the others.

The PermaThread Index lists them all. My favorite is the Basic Folk Library PermaThread. I also like the DTStudy threads which are edited studies of the songs in the Digital Tradition.

-Joe-