The Editor’s list recently ran a post on recommended resources for writers.
As an editor, I’m sure she has see her fair share of writing craft books. Here are some that she reviewed. I would highly recommend clicking on the link and reading her reviews.
The Writer’s Digest Handbook of Novel Writing
Get That Novel Written
The Synonym Finder
Shorter Oxford English Dictionary: Sixth Edition
American Dictionary of the English Language
The Chicago Manual of Style, 16th Edition