Mobilizon - A free and federated tool to get our events off Facebook
TechEvents.co - Tech and startup events aggregator
Mixily - Hosting your event just got easier.
Facebook Local - Discover places to go and events happening near you
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