John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
Wallperizer - Wallperizer is a desktop wallpaper changer.
Variety Wallpaper Changer - Variety is a wallpaper changer for Ubuntu which is featureful, yet slim and very easy to use.
CommandLine Wallpaper Changer - Change Wallpaper From little Command Line Application
Wallpaper Cycler - NuonSoft WallpaperCycler is a powerfull utility to manage all your wallpapers and to automatically cycle between your wallpapers.
Artpip - Artistic wallpaper for your desktop, refreshed daily.