Becrux Wally - Wally is a Qt4 wallpaper changer, using multiple sources like files, folders, FTP remote folders, Flickr, Panoramio, Ipernity, Photobucket, Buzznet, Picasa, Smugmug, Google, Vladstudio and deviantART images. Now it's available in many languages!!
Variety Wallpaper Changer - Variety is a wallpaper changer for Ubuntu which is featureful, yet slim and very easy to use.
Artpip - Artistic wallpaper for your desktop, refreshed daily.
John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
AutoWallpaper - Using AutoWallpaper:
Wallpaper Engine - Wallpaper Engine enables you to use live wallpapers on your Windows desktop.