The BLM site has some nice wallpapers for you computer.
See these photos from the BLM's National Landscape Conservation System every day -- on your computer monitor. Just follow this link, then click on the photo you want. You can then right-click on the photo, and choose "Set as Background" (or similar wording, depending on your browser). On a Mac with Safari browser, control-click on the photo and select "Use Image as Desktop Picture." (Note: Due to quirks in our web management software, if you download the photos you may need to change the ".gif" at the end of the file name to ".jpg.")
http://www.blm.gov/ca/st/en/prog/blm_sp ... paper.html