CodeAcademy teaches programming and coding in online, free and interactive lessons.
Coursera has over 400 courses in more than 20 categories, created by 85 Universities from 16 countries. Their courses are available in 12 different languages.
Duolingo offers completely free language education.
EdX was created by Harvard and MIT and offers MOOCs (Massive Open Online Courses) and interactive online classes in law, history, science, engineering, business, social sciences, computer science, public health, and artificial intelligence.
MIT has their own MOOCs (Massive Open Online Courses) with more than 2,000 courses available.
MOOC List aggregates MOOCs (Massive Open Online Courses) from different providers. Browse for a course by topic (initiative) university, language, country, or multiple criteria.
Open Culture aggregates free courses and audio books found on the web and hosts them on the site.
Stanford has online and open courses which allow you to work at your own pace.