In my case, the minimal effort required was when I provided a few suggestions, months ago, on the direction the artist (the wonderfully excellent Chris McGrath) might take for Children of Scarabaeus, the sequel to my debut novel, due out April 2011. In the first book, my protagonist Edie is a sheltered young woman who finds herself out of her depth. She is protected by - and in turn protects - an ex-con named Finn.
In book 2, Edie finds her footing. I suggested that she should be in a more "assertive" pose for this cover. More importantly, surely, I suggested that Finn should have a bigger gun. Voilà!
(He has two guns!)
Book covers on the shelves these days just get better and better, it seems to me. I would call many of them works of art. Thank the marketing departments of publishing houses for that, and of course the talented artists involved.
What are your favorite recent covers? How about old classics? Ever thought the book was going to be one thing because of the cover, and it turned out to be something else entirely? Or where the characters depicted were nothing like you imagined them after reading the book?