Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.
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.
Bigtent - BigTent is a web-based organization and communication portal for groups.
Morse - Create, shout out, and discover nearby events in real time
Nabble - Nabble is a forum software that are embeddable and fully customizable with scripting language.
Upcoming.org - A simple way to share and discover interesting events