Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Mobilizon - A free and federated tool to get our events off Facebook
Cvent - Cvent's event management software provides event planners with a complete solution to increase event attendance and decrease event costs.
DownToMeet - DownToMeet is a platform to organize, find, and attend group events.
Ticket Tailor - Ticket Tailor is an easy-to-use event ticketing platform that allows event organizers of all shapes and sizes to sell tickets online.