Burning Man
Burning Man is a one-week annual festival held on the week prior to and including Labor Day weekend. Its current location is on the playa of the Black Rock Desert in Nevada, 120 miles north of Reno. The city (housing ~30,000 residents in 2002) is a temporary experiment in community, radical self-expression, and radical self-reliance.
Some primary foci of the festival: leave no trace (an ecological concept), and a commerce-free event (well, excluding coffee and ice which benefit the local Empire/Gerlach school system, and the onsite commissary for staff).