Various tools for writers operated by the ReAnimus Press crew:

Heinlein
How To Improve Your Speculative Fiction Openings, by Robert Qualkinbush

General:

Space Travel - A Science Fiction Writer
Of Worlds Beyond, by Lloyd Arthur Eshbach, ed.
The Craft of Writing Science Fiction that Sells, by Ben BovaFootprints on Sand, by L. Sprague de Camp and Catherine Crook de CampSF in Dimension, by Alexei and Cory PanshinHeinlein in Dimension, by Alexei PanshinMore Issues at Hand, by James Blish (as William Atheling, Jr.)In Search of Wonder, by Damon KnightAnthopology 101: Reflections, Inspections and Dissections of SF Anthologies, by Bud WebsterHaving Relationships With Characters on the Road to Great Fiction, by Andrew BurtModern Science Fiction, by Reginald Bretnor, ed.The Science Fiction Novel, by Basil Davenport, Robert A. Heinlein, C. M. Kornbluth, Alfred Bester, and Robert BlochGalaxy Magazine: The Dark and the Light Years, by David L. RosheimThe Issue at Hand, by James Blish (as William Atheling, Jr.)