Milo - Shake to instantly meet community members near you
Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.
Groups.io - Email and web based discussion group software, includes archiving, emails, wiki, polls, file...
Jira - The #1 software development tool used by agile teams. Jira Software is built for every member of your software team to plan, track, and release great software.
Gaggle Mail - Gaggle Mail is a simple and easy to use email list manager.