Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Get Together - Get Together is an open source event manager for local communities.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Bylde - Bylde is a SaaS platform you can use to Start, Manage and Grow your groups and communities.
Guestboard - Lead powerfully-organized group events with Guestboard – a modular event platform that gives groups of 10-1000+ people a central space to coordinate, build excitement, and save money. No more crazy email threads. No more massive group texts.
Kickstarter - Kickstarter is the world's largest funding platform for creative projects. A home for film, music, art, theater, games, comics, design, photography, and more.