On Writing, by Stephen King; Characters & Viewpoint, Orson Scott Card; The Complete Handbook of Novel Writing, Writer's Digest (contributing authors); How to Write SF & F, Orson Scott Card; Self-Editing, Browne & King; Comedy Writing Secrets, Mel Helitzer & Mark Shatz
On Writing, by Stephen King
I read this one just to see his experience with the writing and publishing scene. Though, things have changed since his early years. I think the thing I picked up most was his rule about using "he said."
Characters & Viewpoint, by Orson Scott Card
This was worth the read. I learned about the different viewpoints, why they're affective in their ways, and how different genres can use them better than others. Since I write humor, I spent much time studying the third-person and omniscient views, for writing novels; for work without dialogue, I'd go with first-person.
How to Write SF & F, by Orson Scott Card
This was a helpful book for discerning the difference between SF & F, how to plan them, describing worlds, systems and laws (physics, if necessary). He also addresses the difficulty in balancing exposition with the need to present a world like or unlike ours and keeping the pace of the tale.
The Complete Handbook of Novel Writing, Writer's Digest Books (various authors)
This one as helpful, more so for tips, and not as in-depth as others. It touches on different genres, writing styles, and author experiences.
Self-Editing For Fiction Writers, by Browne & King
A helpful book for anyone who wants to attempt editing their work. Editing can be daunting, and I've overdone it. I've learned from this work the most important thing is consistency in storyline (things make sense altogether), and reading comprehension. If someone can't understand what is going on because of silly mistakes (misplaced commas, excessively long sentences, too many adjectives), they'll get lost, confused, and likely give up.
Comedy Writing Secrets, Mel Helitzer and Mark Shatz
This is my favorite book on content and format specific writing. I've learned quite a bit from this book about setting up surprise and structure for humor writing. It really is an art of its own. There are other books that cover humor writing, but this is the only one I've read so far. It covers how to set up jokes. What I've realized, though, is it is difficult to write humor fiction that is witty and quick, with all the words needed to describe a scene; like someone telling a long joke and you're thinking, "Ugh, come on, just get to the point." Can lose it quick.
I've read other books, about writing for comic strips, essays, and some college-required material. But these are the ones I have on hand at the moment.