The Answer Bank - The Answer Bank is the UK’s leading question-and-answer site.
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
wikiHow - wikiHow is a wiki based collaboration to build the world’s largest, highest quality how to manual.
Event Hunt - Startups and Tech Events Curated By Locals
AllAnswered - Your Team's Collective Brain All-In-One Knowledge Management System Wiki + Q&A + Workflow + AI
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets