TechEvents.co - Tech and startup events aggregator
Eventjoy - The Easiest Way To Organize An Event
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Meetup for iOS and Android - Discover groups that are all about the things you love
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.