You will not find a single book on this site that I have not myself read. These are the books I have used in my quest to become a better writer. Perhaps they will help you as well.

Self-Editing for Fiction Writers	Renni Browne Dave King	This one is exceptional. Take any first draft and turn it into publishable material with this great editing guide. Improved my writing one hundred percent. This is not a grammar guide. It is much deeper.
The Elements of Style	William Strunk, Jr and E.B. White	Here's the grammar guide. If you need it, buy it. This is THE classic text on the subject.
The Creative Writer's Style Guide	Christopher T. Leland	This style guide takes into account specific aspects of fiction, including the differences from other types of writing, the handling of slang and pop culture, and other useful things. Highly recommended for fanfiction writers.
Telling Lies for Fun & Profit	Lawrence Block	This is such a classic, you'll read it many times over. I wish I had read it years ago. Absolutely a must have.
How to Write Science Fiction & Fantasy	Orson Scott Card	A great guide for science fiction writers from the brilliant author of Ender's Game. It's really helpful to learn how concepts like that are developed.
The Writer's Guide to Creating a Science Fiction Universe	George Ochoa Jeffrey Osier	This is outstanding. It gives all the details that Card didn't give in his sci-fi guide, and the two compliment each other wonderfully. This has very little about how to write, plot, or where to find ideas (which is what Card taught us) but it is excellent in the creation of a universe. This book delivers what it promises.
Worlds of Wonder How to Write Science Fiction and Fantasy	David Gerrold	Winner of the Hugo and Nebula Awards and the writer of The Trouble With Tribbles, Gerrold shares valuable advice on writing speculative fiction that sells. Excellent examples of specific techniques using Gerrold's own work and that of the great Robert A. Heinlein. (It's also the third or fourth book I've read that quotes the phrase "the door dilated.")
Aliens and Alien Societies	Stanley Schmidt Ben Bova, Editor	Astrobiology for the writer. A detailed study on how to create aliens and the worlds they hail from.
World-Building	Stephen L. Gillett Ben Bova, Editor	A detailed guide for creating fictional planets that even scientists will believe.
Borderlands of Science	Charles Sheffield	Even more science for the writer. Helpful and entertaining for fans of science fiction as well as writers.
The Science of Science-Fiction Writing	James Gunn	This is another how-to guide for science fiction, including writing advise and examples from classic science fiction.
Characters and Viewpoint	Orson Scott Card	This is very helpful for developing characters and using them properly. I especially enjoyed it since I had already read all the novels used as examples.
Dynamic Characters	Nancy Kress	Don't write about boring characters. Write about exciting characters that hold the reader's attention.
Writing Dialogue	Tom Chiarella	Get the 'he said/she said' down pat, and your characters will have conversations that are natural, interesting, and easy to read.
The 38 Most Common Fiction Writing Mistakes	Jack M. Bickham	This is excellent. A great thing to read while in the development stage in any project. Character chapter is particularly well done.
Creating Character Emotions	Ann Hood	This one helped me a great deal, but I can see how it might frustrate some. Be prepared to think, because she doesn't hand out easy answers. "Don't say blah," she'll tell you, but there aren't any suggestions for what to say instead. So you'll have to think for yourself, but this will help you do so. Very helpful in avoiding cliches.
Getting Into Character	Brandilyn Collins	This one was fun. A great way to study character motivation and character mannerisms. Excellent. Really excellent. Takes what actors already know and transforms it for the writer.
45 Master Characters	Victoria Lynn Schmidt	Character design issues? Here's a fun way to cheat. This one works best when combined with Getting Into Character. Together, they work wonders.
How to Write a Book Proposal	Michael Larsen	This one is for non fiction, and is a standard guide. If you need it, you need it.
Visions and Revisions	Lyn Walker	Full of harmless little writing exercises, some of which may even inspire a story.
Beginnings, Middles & Ends	Nancy Kress	Really a helpful book. Goes well with Dynamic Characters
The Writers Complete Fantasy Reference	Terry Brooks Writer's Digest	Very helpful in creating a fantasy universe.
Everyday Life in the Middle Ages	Sherrilyn Kenyon	European middle ages, of course. Very informative. Bought it to look stuff up, read much of it.
Everyday Life Among the American Indians	Candy Moulton	A great writer's reference which makes your story's setting authentic. Especially helpful to Star Trek fanfiction writers dealing with Chakotay's heritage.
Story Starters	Lou Willett Stanek, Ph.D.	This is the cure for writer's block. If you don't have an idea, pick one of these at random and go. No more excuses!
The Deer on a Bicycle	Patrick McManus	This is just plain fun to read. Learn from a great humor writer as he shares how he came to be a great humor writer.
Plot	Ansen Dibell	This is great help if you have a character in your mind but nothing in particular to do with him. Learn how to build a plot without leaving any hanging threads.
The First Five Pages	Noah T. Lukeman	Another fabulous book which helps you see your hard work through an editor's eyes. A must read.
Zen in the Art of Writing	Ray Bradbury	A nice cure for writer's block. Thoughts on writing from a master.
The Art and Craft of Poetry	Michael J. Bugeja	A very helpful guide on poetry. Both practical discussion of form and helpful exercises to coax the muse from hiding.
The All-Breed Dictionary of Unusual Names	Gloria S. Jarrett	Okay, so what's a dog breeding book doing on this list? It's great for naming aliens as well as dogs. Enjoy.
Rewrite Right	Jan Venolia	I can't stress this enough. There are no great writers. Only great rewriters. Here's another editing method, though not strictly for fiction.
Writer's Digest Handbook of Magazine Article Writing	Jean M. Fredette	Helpful advice for those trying to make a living.
How to Write a Dirty Story	Susie Bright	This goes a little far, but has some helpful advice. This is meant for writing erotica, not just a sex scene in a mainstream novel. Good for fanfiction writers.