Facebook Events - Facebook Events enables businesses to organize gatherings, manage invitations and send notifications and reminders to their audience.
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.
TechEvents.co - Tech and startup events aggregator
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Cvent - Cvent's event management software provides event planners with a complete solution to increase event attendance and decrease event costs.