I don't generally know alot of the artist names. Looking at Richard Powers' website, there are alot of great covers there. I've seen lots of them online, and I have a pile of Clifford Simake Paperbacks sitting next to me that has a couple of them in it:
I have some of the Donald A. Wollheim Year's Best anthologies that he did:
Regarding the covers in my last post, here's another Astounding cover from around that time that I fine really menacing: