NationBuilder - The world's first platform for leaders, handcrafted from scratch to help you grow your community and lead them to action.
Stack Overflow - Community-based Q&A part of the Stack Exchange platform.
Crowded Communities - The all-in-one community platform.
The Answer Bank - The Answer Bank is the UK’s leading question-and-answer site.
FUEL CYCLE by Passenger - Think Passenger builds online platforms that allow brands to connect, create and communicate with key stakeholders.
Askalot - Askalot is a next generation CQA (Community Question and Answer) system.