1. Sporcle
  2. MIT Open Courses
  3. Stanford’s Free Course
  4. Coursera
  5. Wolfram|Alpha
  6. 99% Invisible
  7. Instructables
  8. Stanford Encyclopedia of Philosophy
  9. The New Boston
  10. Less Wrong
  11. Quora
  12. CosmoLearning
  13. Tech-Recipes
  14. Snopes
  15. Thinking Allowed
  16. HowStuffWorks
  17. ThinkTutorial
  18. Academic Earth
  19. Mental_floss
  20. Duolingo
  21. Project Euler
  22. Codecademy