TeamSnap - Sports Team, Club & League Management Software & Apps
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
CoachHippo - The ultimate membership management tool for managing your club, nonprofit and organisation. Collect payments online. - Get started for free!
Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Simpler Sport - Save time managing your sports team
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets