Most recently, Eric Hanson provided the wonderful cover for John Waters' autobiography. As always, I'm a fan of books like this that don't make use of a boring photographic portrait on the front.
Other Hanson work...
(That's Baby Leg by Brian Evenson, from Tyrant Books)
Eric's blog, full of his illustration work, is here. I like his style: to me, his work sits at the third corner of a triangle, the other two corners of which are Quentin Blake and funky old jazz album covers.
UPDATE: Eric himself added some useful info in the comments, which I'll append here: "Waters is a real mensch, very nice to work with. Susan Mitchell, the art director at FSG deserves much of the credit for how great it looks, but it was Waters who insisted on using the pencil sketch instead of the painting I did from it. It made all the difference. I recently did an interview on the Faceout Books blog about the process. I'm also flattered that you enjoyed the book that I wrote, A Book of Ages. It was fun to write, and Whitney Cookman, my art director at Random House, was nice enough to use my illustration on the cover as well.
My first book covers were the icons I did for the Chic Simple books published by Knopf in the '90s. Art directed by Robert Valentine."