Mobilizon - A free and federated tool to get our events off Facebook
Facebook Events - Facebook Events enables businesses to organize gatherings, manage invitations and send notifications and reminders to their audience.
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
DownToMeet - DownToMeet is a platform to organize, find, and attend group events.
Picatic - Picatic encourages event organizers to create a custom website, sell tickets and then determined their cost of use. Selling out events is easy with Picatic.