Get Together - Get Together is an open source event manager for local communities.

EventsApp - A simple concise app for creating and sharing events.

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

Event Hunt - Startups and Tech Events Curated By Locals

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.

Calendify - Calendify is an event community where you can share, publish, and subscribe to event calendars. It helps you to stay informed about what you are interested in and what is yet to come.