Various tools for writers operated by the ReAnimus Press crew:

The Craft of Writing Science Fiction that Sells, by Ben Bova
Of Worlds Beyond, by Lloyd Arthur Eshbach, ed.

General:

Specific to Smashwords:

More Issues at Hand, by James Blish (as William Atheling, Jr.)
How To Improve Your Speculative Fiction Openings, by Robert Qualkinbush
Anthopology 101: Reflections, Inspections and Dissections of SF Anthologies, by Bud WebsterHaving Relationships With Characters on the Road to Great Fiction, by Andrew BurtSpace Travel - A Science Fiction WriterIn Search of Wonder, by Damon KnightThe Issue at Hand, by James Blish (as William Atheling, Jr.)Staying Alive - A WriterGhosts of Engines Past, by Sean McMullenKaheesh, by Jerry SohlBut Wait.... ThereCreating Short Fiction, by Damon KnightKafkaTimeshare: Second Time Around, by Joshua Dann