Pipedrive - Sales pipeline software that gets you organized. Helps you focus on the right deals, so easy to use that salespeople just love it. Great for small teams.
Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.
Zoho CRM - Omnichannel CRM for Businesses of all sizes
TidyHQ - Organization management tool to support membership, subscriptions, event planning, and outreach.
Freshsales CRM - A full-fledged CRM for high-velocity sales teams.
Nabble - Nabble is a forum software that are embeddable and fully customizable with scripting language.