GoConqr - Social learning platform for educators & learners
Investopedia - Investopedia has a lot of information to share with business mind people.
Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.
Fandom - The entertainment site where fans come first.
Anki - Anki is a program which makes remembering things easy. Because it's a lot more efficient than traditional study methods, you can either greatly decrease your time spent studying, or greatly increase the amount you learn.
Wikiful - Wikiful is an online platform that makes it easy to build and share a wiki.