Muzei - Muzei is a live wallpaper that gently refreshes your home screen each day with famous works of art.
Splashy - Breathtaking, auto changing wallpaper app for macOS, Windows, Linux, iOS & Android
Variety Wallpaper Changer - Variety is a wallpaper changer for Ubuntu which is featureful, yet slim and very easy to use.
Splashify - Beautiful desktop wallpapers for Mac and Windows
John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
Irvue - (previously Unsplash Wallpaper) Gorgeous wallpapers on your Mac.