Eventjoy - The Easiest Way To Organize An Event
Wikivoyage - the free worldwide travel guide that anyone can edit.
Meetup for iOS and Android - Discover groups that are all about the things you love
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.
TechEvents.co - Tech and startup events aggregator
Triptipedia - Triptipedia is a free collaborative encyclopedia of travel tips, where everyone can browse, save and share tips for better travel!