I was recently directed to the Smashwords ebook store by a colleague, and found several books there on book publishing and promotion that were downloadable at no cost.

The Smashwords Book Marketing Guide
By Mark Coker
This free book marketing primer provides authors actionable advice on how to market their Smashwords books. It starts with an overview of how Smashwords helps promote your book, and then provides a series simple do-it-yourself marketing tips.

ePublish: Self-Publish Fast and Profitably for Kindle, iPhone, CreateSpace and Print on Demand
By Steve Weber
Sell your book NOW, in eBook and paperback! Book sales guru Steve Weber tells you the secrets big publishers don’t want you to know

Plug Your Book! Online Book Marketing for Authors, Book Publicity through Social Networking
By Steve Weber
Get massive exposure for your book, no special computer skills needed, trade published or self published, fiction or nonfiction.

I’ve downloaded these to my Kindle and will be perusing them in a few weeks when I head on vacation. If you read them before me, comment and let me know what you think.