Split out more or less by topic.
Primer – Because it’s the most rigorous use of time travel I’ve seen anywhere, particularly for a visual medium
The Cross-Time Accountants Fail to Kill Hitler Because Chuck Berry Does the Twist – I can’t tell you why this is recommended without spoiling it. If the title isn’t enough to intrigue you, your loss.
Babel-17 – Because you’ll understand why people keep going back to the Sapir-Whorf hypothesis when it is wrong, wrong, wrongity wrong.
Embassytown – Because it’s brilliant, and does Sapir-Whorf correctly
Semantics – Good solid text book-y resource
Understanding Minimalist Syntax: Lessons from Locality in Long-Distance Dependencies – If you really want to dig into a modern theory of Syntax.
Steven Pinker – Not because he’s totally reliable, but because he’s a good intro to lay people and will help keep you from making an ass of yourself.
Acting One – Obviously not everything is going to be directly useful for writers, but I really think knowledge of basic character-development and scene analysis that goes into a lot of beginning acting and directing instruction is potentially hugely useful to writers. You can get a lot of the same information in how-to writing books, but I find the wankery in writing books to be much, much higher.
Because it’s Good
The Hundred Thousand Kingdoms – And really, anything by N.K. Jemison. She’s fantastic.
Luther – Because it does really fantastic thematic work without shouting “Hey, we’re doing fantastic thematic work.” And then in the second season, they make the hard, correct decisions rather than the obviously fun ones.
Leviathan – If you’re not sure whether you like Steampunk and want to find out in a way that doesn’t take a lot of time, go for a solid YA novel
The Name of the Wind – The prose is lovely, the world building fantastic, the tropes nicely played with, and the interaction between frame and narrative fascinating.
Udacity – because free online classes are awesome, and these are really well done