5. Khan Academy
Khan Academy, like Coursera, provides lots of courses for free. The difference is that while Coursera focuses on University courses, Khan Academy on both high school and university courses. And it's courses are available year round, unlike Coursera's which are available at specific periods of the year.
Memrise is your perfect free solution to learning any (major) language. It has the best research-backed effective interactive means of learning a language. It's free and have full featured Android and iOS apps. It will take you from the beginner's level in any major language to a proficiency level, and you will be amazed by the depth and breadth of the language learning curriculum it has. I use it for my French learning. You can also learn German, Spanish, Chinese and many other languages on Memrise.