For those of you who don't know the work of Richard M. Powers, make a trip to the sci-fi section of your nearest used bookstore immediately. Powers pretty much single handedly reinvented the look of the science fiction book cover. Drawing inspiration from surrealist and modern art (Miro, Tanguy, Picasso), rather than traditional pulp depictions of spaceships and aliens, Powers' cover illustrations emphasized the psychological and trippy-er aspects of the genre. Largely forgotten (except by enthusiasts), in the 1940s and 50s he was THE go to guy for mass market science fiction illustration. Some of his work was recently represented in Steven Brower's superb study of mass market book covers: Breathless Homicidal Slime Mutants. He should really have his own book. Read more about him here.
The covers below were culled are from the collection of occasional Spine Out guest blogger and knower of all things of interest, Tim Cronin.