I'm certain that there are more than four amazing writing books out there (I've actually probably read more than a few of those) but when it comes to fantasy writing, and to what I want to post on my blog, I've limited my selection of Amazing Writing Books to these four (not in any particular order).
Stephen King's On Writing:
This book gives you a look at the
life of a writer, the trials and
errors, the ups and downs, the
work you have to put into the
craft before you get a paid (usually).
It's very insightful, interesting
and helpful. Other than just
King's life story, it holds pointers
and lessons in writing.
Orson Scott Card's How To Write Science Fiction & Fantasy:
This is an awesome book devoted
to the craft of writing science
fiction and fantasy. It delves into
character and world creation
while giving help on the subject
of writing well and exploring the
business of writing for the novice
Orson Scott Card's Characters & Viewpoint:
This book may not be specifically
aimed towards science fiction
and fantasy authors, but it is
helpful when writing any story.
I find that Card explains things
well and thoroughly, leaving
the reader with few questions
and new tools to create better
characters in their tales.
Robert Masello's Writer Tells All:
This is an awesome book
that explores all
elements of writing
a novel, from the
birth of an idea,
through it's publication
and beyond. This is a book that will guide an author through every stage of writing and getting published. (Also check out Robert's Rules of Writing for good tips).