Arguing From Ignorance: A YouTube channel that aims to clarify misconceptions towards science.
Ask Science: A reddit page for scientific inquiries.
Doomsday Clock: A countdown to catastrophe – hand positioning changes to reflect current world events.
DuoLingo: A website that allows you to learn new languages with relative ease.
Khan Academy: Because education doesn’t have to cost anything.
Kurzgesagt: A high-quality Youtube channel that explains science simply.
Less Wrong: A community for the rationally-minded.
PubMed: Open access medical journal database.
Siyavula: Open-source textbooks for junior high & high school math/science.
TED: Ideas Worth Spreading: A series of talks on a variety of topics related to Technology, Entertainment, and Design.
UCDavis ChemWiki: An excellent resource which covers the main branches of chemistry.