webilder is a convenient little application that downloads and sets flickr photos as your desktop wallpapers. webilder no longer provides repository sources for either gutsy or hardy. But getdeb provides Debian packages for both gutsy and hardy including 32 & 64 bit architectures.
Goto http://www.getdeb.net/app/Webilder and download debian packages that correspond to your processor architecture & ubuntu version. Now install both webilder & webilder-gnome packages using following command.
sudo dpkg -i webilder*.deb
Click on your gnome panel add choose +Add to Panel menu item. You will see list of gnome panel applets. Select Webilder Desktop Applet and drag and drop it on to gnome panel. Right click on webilder icon on gnome-panel and select Download Photos. webilder by default downloads interestingness photos from flickr. These interestingness photos are usually high quality photos tagged by flickr community. Beware that these photos some times contain material that may be NSFW. You can configure webuilder to download photos with specific tags.
Enjoy your beautiful desktop.
Offical webilder site.