Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Odoo - An all-integrated business app suite to unleash your growth potential.
Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Naologic - Speed up collaboration and work more securely with your partners, customers, and vendors by creating custom apps without a development team.