Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Event Calendar App - A simple, easy to manage, way of displaying events
DownToMeet - DownToMeet is a platform to organize, find, and attend group events.
Zoho Backstage - Plan, run, and analyze your event— all from one place
Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.
Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform