Zelos - A very simple app for mobile teams - tasks and chats on desktop and mobile.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Cvent - Cvent's event management software provides event planners with a complete solution to increase event attendance and decrease event costs.
GroupServer - Email lists, with an integrated web interface, and control.
Ticket Tailor - Ticket Tailor is an easy-to-use event ticketing platform that allows event organizers of all shapes and sizes to sell tickets online.