If you like the Bing images and would like to download them, including some of the old one’s, here is how you can do it.
Open Bing.com. In the top right part of the screen, click on Country.
Now in the country listings, click United States (English).
Now go towards the bottom right corner and click on the arrows to see wallpapers from previous dates.
To save them to your desktop, right on the image and click on Save Background As.
Firefox users can do so through Tools > Page Info > Media.
Also check out Bing Downloader.