Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Wikivoyage - the free worldwide travel guide that anyone can edit.
Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
Tripadvisor - The Tripadvisor mobile app is available for the Android and iOS platforms. It can be used to create reviews of hotels, restaurants, and to chat with other travelers on Tripadvisor forums.
pretix - pretix helps you to sell tickets for your event in an easy way. It supports multi-lingual events and provides a wide range of features
WikiOverland - WikiOverland is the community encyclopedia of Overland Travel.