Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.

Nightout - The standard in event ticketing and marketing by NIGHTOUT

Eventbrite - Discover Great Events or Create Your Own & Sell Tickets

Airbnb - Book unique places to stay and things to do.

Bigtent - BigTent is a web-based organization and communication portal for groups.

TickPick - Purchase tickets to your favorite events with no hidden fees