Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
RoomForTea - A female-friendly housing network in London, UK.
Event Hunt - Startups and Tech Events Curated By Locals
Travel Diaries - Create your own travel diary to capture your experiences
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Travellar - A social travel app