Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.

Prefer - Professionals you need, from people you know

Nabble - Nabble is a forum software that are embeddable and fully customizable with scripting language.

Warmspace - Tech-powered conversations that transform relationships in work and life.

Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.

Introwise - All-in-one scheduling and business management platform for coaches, tutors and consultants to run their business online.