I save images that make good wallpapers, look cool, or are in danger of disappearing. Most are old, so you can see how screen resolution has changed in the past several years. Check them out by visiting the link on the left under “pages” or by clicking here.
The Dropbox gallery feature is easy to set up and its viewer is nice, but you can’t add captions. I didn’t credit the image authors in the filenames– for finding their origin I recommend TinEye.
Non-endangered images that may or may not be wallpaperable can be seen in my flickr favorites.