Hivemapper - Build maps that reveal changes 🌏
John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
Google NightWalk - An audio Streetview tour around Marseille
Muzei - Muzei is a live wallpaper that gently refreshes your home screen each day with famous works of art.
Cat Street View - Explore Japan... as a cat.
Variety Wallpaper Changer - Variety is a wallpaper changer for Ubuntu which is featureful, yet slim and very easy to use.