TechEvents.co - Tech and startup events aggregator
1up Events - Corporate events as a service
Facebook Local - Discover places to go and events happening near you
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Eventjoy - The Easiest Way To Organize An Event
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.