Like most sci-fi cons, Westercon had an art show. So I decided to link to some of the artists there who were producing art that I thought would work on a book cover (at least, I linked to those who have Web sites--have Web sites, artists!). Some are well-known and fancy, some are obscure, but all push the sci-fi/fantasy themes. And again, Frank Wu, who has won four freakin' Hugo Awards, says he'll gladly inexpensively license an existing piece of art for a cover, so that's always worth asking about.
In the dealer room I found:
And a ton of fancy custom-made objects d'art--a lot of them were very steampunky--plus fabrics. The people who make those might be willing to let you take a photo to put on a book cover as well.
Yesterday, Wu and Sturgeon said that publishers used to just go to sci-fi cons, walk through the art shows, and pick out work they liked for cover. So if you're the publisher now....