Bulk Image Downloader - With Bulk Image Downloader you can download full sized images from almost any web gallery.
John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
Vov Picture Downloader - Download pictures from websites.
Variety Wallpaper Changer - Variety is a wallpaper changer for Ubuntu which is featureful, yet slim and very easy to use.
WFDownloader App - A free bulk image downloader application that also serves as a multi-purpose bulk downloader for your PC.
Muzei - Muzei is a live wallpaper that gently refreshes your home screen each day with famous works of art.