I have never officially attended, but have dropped in for a couple of hours on occasion, at two such events. The one that comes most readily to mind is the Sweets Mill camp, which took place for many years in the hills east of Fresno, CA. Mark Spoelstra, among others, would often attend. Free spirits were about - and in the air and music, dance and storytelling filled many hours, I'm told. Some serious (and no-so-serious) libidinous exercises were known to occur as well, but it was mostly just good natured fun and music. The event, as I'm told, is no more. Some others have seemed rather commercial, a la the one put on by the Kingston Trio each year down in Arizona. Lots of fun, but expensive, if you're a fan.