So there are tons of books out there for writers, and some time ago there was a thread where people talked about their favorite writing books. Trouble is, the only writing book most of us seemed to think was worthwhile was Stephen King's On Writing, with perhaps an exception here or there.

Personally, I find that the books that help me the most with writing have nothing to do with writing -- they are science books, history books, or photobooks of places with scenery that help my imagination. This is apparently the case with a lot of writers. After all, who is going to spend the day reading a book about nothing but grammar rules, most of which you already know, don't need, or aren't necessarily applicable to what you're writing? Likewise, a book of prompts isn't usually going to be fun, because the funnest part of writing is coming up with the story yourself. The hard part is sitting down and actually doing the writing for as long as it takes to finish. There's lots of writing books out there that spell out rules, and these rules can either be false or subjective. Then there's the fluff pieces, ones that really only talk about the "enlightenment" of writing, or something like that, and don't really leave anything substantive on the brain.

So, in other words, what is something that could be in a writing book that would help you, or at least would have helped your past, less experienced self? Or if you can think of any books that do exist that you think would help, feel free to list those.