4chan - 4chan is a simple image-based bulletin board where anyone can post comments and share images.
wikiHow - wikiHow is a wiki based collaboration to build the world’s largest, highest quality how to manual.
Reddit - Reddit gives you the best of the internet in one place. Get a constantly updating feed of breaking news, fun stories, pics, memes, and videos just for you.
Blurtit - Blurtit is a Q&A website. You can ask a question or answer on any question.
Tildes - A non-profit community site driven by its users' interests
AllAnswered - Your Team's Collective Brain All-In-One Knowledge Management System Wiki + Q&A + Workflow + AI