John W. Campbell SF writer and highly influential editor has a free novel available via the Gutenberg Project. With his editorship of Astounding Science Fiction, and the writers and fandom he promoted, Campbell was the one person most responsible for the "Golden Age of Science Fiction." Invaders from the Infinite is unfortunately the third and final novel of a series similar to E.E. Doc Smith's space operas. As a writer Campbell's best work was under the name Don A. Stuart and has a more modern style. His 1938 story Who Goes There, about an alien threat in the Antarctic, has been made into two films.

SF Related - Eight Things New Writers Need To Know by Robert Sawyer. Link from SF Signal.

On Christmas Day my brother reminded me of Bill, The Galactic Hero. Greg Barr, a later roommate of mine, read the first couple pages of the book I had with me and decided it deserved to be read aloud. He read the entire short novel in the student lounge that night ending in the wee hours. My brother and I were discussing Cheech and Chong's routine of Santa Claus visiting the hood, which I hadn't heard, and the excellent writing and dialogue of John D. MacDonald.