Here are some great covers from the golden age of paperback art.
Three from the website "Good Girl Art"
http://www.goodgirlart.com/gallery.html

Williamson was a prolific science fiction writer with a PH.D. in English who taught for many years at Eastern New Mexico State University.

Brown was one of the great writers of the vintage paperback era. He was primarily a writer of science fiction and mysteries.

The early works by writers who later became well known sometimes started out as paperback originals. The first edition of Kurt Vonnegut's "The Sirens of Titan" was released in 1959. The first hardback edition didn't come out until 1961.

Frances Crane was a mystery writer, who wrote a series of novels featuring the exploits of Pat and Jean Abbott. She wrote regularly for the New Yorker, and had an interesting life. She lived in Nazi Germany for several years, and was eventually expelled for her views.
http://en.wikipedia.org/wiki/Frances_Crane

The cover of an early Charlie Chan novel.
http://www.flickr.com/photos/16007871@N00/1270631622/