I guess one could look at US "weekend in the woods" events, like the DC Getaway and its cousins run by other folk clubs (read groups of folkies, not venues), as "fringe" events. One must buy a ticket, which includes a bunk and food for the weekend, but there are few or no "performers" and the music is made by the people attending, with various degrees of structure - none or train songs in location X at 11am type structure.