What are some alternatives?
GroupSpaces - Free Group Website, Membership Database, Listserv Mailing List, Online Group Management Software : GroupSpaces
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Eventbrite - Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Mailman - Mailman is free software for managing electronic mail discussion and e-newsletter lists.
Bizzabo - Bizzabo is the world’s fastest growing event tech company. Our holistic Events Cloud empowers marketers and planners to manage, grow and maximize events.
Basecamp - A simple and elegant project management system.