Stanford Encyclopedia of Philosophy (SEP): The SEP is an excellent free online encyclopedia of philosophy with each entry created by experts in the field.

Internet Encyclopedia of Philosophy (IEP) : The IEP is a non-profit organization that provides open access to detailed, scholarly information on key topics and philosophers in all areas of philosophy.

Philosophy Talk: Ken Taylor and John Perry create incredible podcasts on a wide range of philosophical questions.  It's a perfect resource for a beginner in philosophy.      

Philosophy Bites: A set of podcasts where hosts interview top philosophers on bite sized topics.

Open Yale Courses in Philosophy: A free resource of classes at Yale University in philosophy.

History of Philosophy (without any gaps): Peter Adamson, Professor of Ancient and Medieval Philosophy at King's College London, takes listeners through the history of Western philosophy, "without any gaps." Beginning with the earliest ancient thinkers, the series will look at the ideas and lives of the major philosophers (eventually covering in detail such giants as Plato, Aristotle, Avicenna, Aquinas, Descartes, and Kant) as well as the lesser-known figures of the tradition.

Philosopher's Zone: A radio program that works through issues in ethics, metaphysics, and logic.

Philosophy Now: Philosophy Now is a newsstand magazine for everyone interested in ideas. It aims to corrupt innocent citizens by convincing them that philosophy can be exciting, worthwhile and comprehensible, and also to provide some light and enjoyable reading matter for those already ensnared by the muse, such as philosophy students and academics.

Philosophy for Children: Philosophy for Children's primary purpose is to introduce philosophy into the lives of young people. One of their principal activities are the "Philosophers in the Schools" program, which brings people trained in philosophy into K-12 classrooms to do philosophy sessions with students, our teacher-education workshops, and our parent-education project. Be sure to check out their excellent blog as well. 

Online Learning:

Khan Academy: Khan Academy offers a constantly growing library of free videos that covers K-12 math, science topics such as biology, chemistry, and physics and even a few videos on history.

Smart History: Smart History at Khan Academy is the leading open educational resource for art history. They make high-quality introductory art history content freely available to anyone, anywhere.

EdX: EdX is a non-profit created by founding partners Harvard and MIT. EdX offers MOOCs and interactive online classes in subjects including law, history, science, engineering, business, social sciences, computer science, public health, and artificial intelligence (AI). 

Open Culture: Open Culture brings together high-quality cultural & educational media for the worldwide lifelong learning community.

MIT+K12: An amazing resource that aims to promote STEM education where MIT students create videos that teach basic scientific and engineering concepts to primary school students in an entertaining fashion.

LearnOutLoud: LearnOutLoud is an organization that offers high-quality podcasts and radio shows on a wide variety of subjects, including philosophy, psychology, economics, and history. 

M.I.T. OpenCourseWare: An excellent collection of resources provided by MIT. Through this portal one can access virtually all of MIT courses with corresponding syllabi, lecture notes, and assessments. All the content is accessible free of charge.

Other Interesting Links:

Open University 60-Second Adventures in Thought: These fast-paced animations explain six famous thought experiments, from the ancient Greeks to Albert Einstein, that have changed the way we see the world.

Brila Youth Projects: Brila is a Philosophy for Children charity that supports youth through educational programming that challenges their assumptions about art, ethics, and human connectivity.

Squire Family Foundation: The Squire Family Foundation supports various efforts that are trying to make philosophy more accessible.  The site has an excellent set of resources on pre-college philosophy.

PLATO (Philosophy Learning and Teaching Organization): PLATO advocates and supports introducing philosophy to K-12 students through programs, resource-sharing and the development of a national network of those working in pre-college philosophy. They have gathered an excellent set of resources on teaching philosophy at K-12 level.

SAPERE (Society for the Advancement of Philosophical Enquiry and Reflection in Education): SAPERE advocates ‘the advancement of education for the public benefit, in particular amongst those young persons up to the age of 16 years, by the promotion of the development of their skills in logical thinking and other philosophical techniques so that their personal and social lives are enriched.

Ask Philosophers: You ask. Philosophers answer.

Teaching Children Philosophy: This organization helps adults conduct philosophical discussion with and among elementary school children.

The Information Philosopher (I-Phi): I-Phi is a new philosophical method grounded in science, especially modern physics, biology, neuroscience, and the science of information. It offers novel solutions to classical problems in philosophy, notably freedom of the will, the objective foundation of values, and the problem of knowledge (epistemology).

Mel Thompson: Philosophy and Ethics: Mel writes introductory and popular books on philosophy, ethics and religion and believes that everything should be explored with an open mind.

A Toolkit for Building a Better Mind.