freecampsites.net - Free camping near you. Go camping for free!
Tentrr - Private, bespoke, fully-equipped campsites
Ultimate US Public Campgrounds - The History of the Ulimate US Public Campground Project
Outsite for Retreats - Team retreats and offsites as a service
Campflare - Get notified when there are campsites open at your favorite campground. Its free.
Coworkations - Explore the world without interrupting your career