Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Guides by Lonely Planet - Explore city guides curated by experts.
Facebook Local - Discover places to go and events happening near you
Foursquare City Guide - Foursquare City Guide is a Free to use mobile application that will lead you to the perfect spot anytime anywhere around the world.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Lonely Planet - travel guide book publisher