All rights reserved to the photographers. Permissions being sought.
The fourth is the official cover, as of August 11, 2012, of the Amazon Kindle Edition. The possibility remains of a redesign, either in part or whole, for other e-editions, or a print-version in the future.
If anyone has an image, or better yet, something original of your own to contribute, please do! Meanwhile, please don’t be shy about expressing a preference for one of those already being considered.