Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
Event Hunt - Startups and Tech Events Curated By Locals
Zoho Backstage - Plan, run, and analyze your event— all from one place
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Meetup for iOS and Android - Discover groups that are all about the things you love