When SF became respectable the publishers began buying cover art from a wider range of sources. Some of it was just as bad as the old stuff. Some of it was striking and interesting.
I'd never paid much attention to cover art until I was sorting through my collection one day. Hmm... I went through one of the piles and sorted it by what I arbitrarily thought of as interesting. Some of it was selected because of subject, some for technical execution, some because it was representative of a type. Some, I don't know why. So there.
Anyway, these 20-odd scans are what resulted. I decided, for lack of any other ideas, to group them by decades. There was a bit of guesswork involved here since the books are long gone, but it shouldn't be greatly important.
Here they are. Enjoy! -dlw