I posted a couple days ago, a list of free university course aggregators. I've had several people contact me with individual sites (such as MIT Open CourseWare), which wasn't the intent of the original post. I've started to compile a list of popular free online education resources, but user Fletch71011 just posted a pretty good list on reddit. I've included his and have added many others:
Reddit Resources - Reddit's List of the best online education sources
Khan Academy - Educational organization and a website created by Bangladeshi-American educator Salman Khan, a graduate of MIT and Harvard Business School. The website supplies a free online collection of micro lectures stored on YouTube teaching mathematics, history, healthcare and medicine, finance, physics, chemistry, biology, astronomy, economics, cosmology, organic chemistry, American civics, art history, macroeconomics, microeconomics, and computer science.
Coursera - Coursera partners with various universities and makes a few of their courses available online free for a large audience. Founded by computer science professors, so again a heavy CS emphasis.
Wolfram Alpha - Online service that answers factual queries directly by computing the answer from structured data, rather than providing a list of documents or web pages that might contain the answer as a search engine might. Unbelievable what this thing can compute; you can ask it near anything and find an answer.
Udacity - Outgrowth of free computer science classes offered in 2011 through Stanford University. Plans to offer more, but concentrated on computer science for now.
MIT OpenCourseWare - Initiative of the Massachusetts Institute of Technology to put all of the educational materials from its undergraduate- and graduate-level courses online, partly free and openly available to anyone, anywhere.
Open Yale Courses - Provides free and open access to a selection of introductory courses taught by distinguished teachers and scholars at Yale University.
Think Tutorial - Database of simple, easy to follow tutorials covering all aspects of popular computing. Includes lots of easier, basic tasks for your every day questions or new users.
Duolingo - For all of your language learning needs.
Memrise - Online learning tool that uses flashcards augmented with mnemonics—partly gathered through crowdsourcing—and the spacing effect to boost the speed and ease of learning. Several languages available to learn.
Livemocha - Commercial online language learning community boasting 12 million members which provides instructional materials in 38 languages and a platform for speakers to interact with and help each other learn new languages.
edX - Massive open online course platform founded by Massachusetts Institute of Technology and Harvard University to offer online university-level courses in a wide range of disciplines to a worldwide audience at no charge. Many other universities now take part in it, including Cal Berkeley. Differs from most of these by including "due dates" with assignments and grades.
Education portal - Free courses which allow you to pass exams to earn real college credit.
uReddit - Made by Redditors for other Redditors. Tons of different topics, varying from things like science and art to Starcraft strategy.
iTunes U - Podcasts from a variety of places including universities and colleges on various subjects.
Stack Exchange - Group of question and answer websites on topics in many different fields, each website covering a specific topic, where questions, answers, and users are subject to a reputation award process. Stack Overflow is used for programming, probably their most famous topic. Self-moderated with reputation similar to Reddit.
Wikipedia - Collaboratively edited, multilingual, free Internet encyclopedia. Much better source than most people give it credit for, and great for random learning whenever you need it. For those looking for more legit sources for papers and such, it is usually easy to jump to a Wikipedia page and grab some sources at the bottom.
Wikiversity -Wikiversity is a Wikimedia Foundation project devoted to learning resources, learning projects, and research for use in all levels, types, and styles of education from pre-school to university, including professional training and informal learning. We invite teachers, students, and researchers to join us in creating open educational resources and collaborative learning communities. To learn more about Wikiversity, try a guided tour or start editing now.
Open Culture - Open Culture brings together high-quality cultural & educational media for the worldwide lifelong learning community. Web 2.0 has given us great amounts of intelligent audio and video. It’s all free. It’s all enriching. But it’s also scattered across the web, and not easy to find. Our whole mission is to centralize this content, curate it, and give you access to this high quality content whenever and wherever you want it. Free audio books, free online courses, free movies, free language lessons, free ebooks and other enriching content — it’s all here. Open Culture was founded in 2006.
Various Youtube series -
Smarter Every Day,
If you know of any more, let me know and I may add it!