The Answer Bank - The Answer Bank is the UK’s leading question-and-answer site.
Cocorico - Cocorico is a state-of-the art Open Source solution to create an Airbnb or Blablacar for anything.
wikiHow - wikiHow is a wiki based collaboration to build the world’s largest, highest quality how to manual.
Sharetribe - Build your online marketplace business. You don't need a developer.
AllAnswered - Your Team's Collective Brain All-In-One Knowledge Management System Wiki + Q&A + Workflow + AI
JaJuMa-Market - All-In-One Multi-Vendor / Online Marketplace Solution. Various Business Models supported.