Here's my list of great writing how-to and writing inspiration books.
Techniques of the Selling Writer ~ Dwight V Swain
Very concrete, and to the point information about writing popular fiction. All the information in this book is invaluable. His chapter on 'Selling your Stories' is terse and to the point:
1 Study your markets.
2. Get manuscripts in the mail.
3.Keep them there.
On Writing ~ Stephen King
(That's the hard back ISBN. It's also in trade paperback.) A wonderfully sane, down-to-earth book.
How to Write a Dirty Story ~ Susie Bright.
The title says it all. Readable and down-to-Earth, with an excellent section on the realities of making a living from writing.
Elements of Arousal - How to Write and Sell Gay Men's Erotica ~ Lars Eightener
Long out of print but well worth the search. Don't be put off by the title - this book offers excellent writing advice for any genre.
Bestseller ~ Celia Brayfield
Excellent sections on what makes a story work and what readers expect from a story. Good writing advice too.
Guide to Fiction Writing ~ Phyllis A Whitney
A very practical outlook and no nonsense approach.
If you Want to Write ~ Brenda Ueland
This is the book to read when you're feeling guilty about not writing''enough'.
Also for inspiration and ideas:
Hot and Bothered ~ Wendy Dennis ISBN 0-586-21440-2
A Natural History of Love ~ Diane Ackerman ISBN 0-679-76183-7
A Natural History of the Senses ~ Diane Ackerman ISBN 0-679-73566-6