1. Librelist is a free as in freedom mailing list site for open source projects

  2. Tinder with your friends. Party in a group.

  3. PHP-based CMS built for forums and community building.

  4. GNU social is communication software for both public and private communications.

  5. Bizzabo is the world’s fastest growing event tech company. Our holistic Events Cloud empowers marketers and planners to manage, grow and maximize events.

  6. Airmail is a lightweight and lightning fast mail client for Mac.

  7. Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.

  8. An email address for your group. Discuss. Debate. Organise. All with email.

  9. Where developers come to talk.

  10. ccGenie turns a mountain of emails, attachments, and links into an organized project so that you...

  11. Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.

    freemium $11.99 / Monthly (Per user - Premium)

  12. Unison is a group communication tool that helps organizations connect and organize their people.