Easy Poster Printer - Ever wanted to create your own poster?
John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
Rasterbator - Wall art from any image
Muzei - Muzei is a live wallpaper that gently refreshes your home screen each day with famous works of art.
Block Posters - A free poster maker to create massive wall posters from your own images! Free!
Variety Wallpaper Changer - Variety is a wallpaper changer for Ubuntu which is featureful, yet slim and very easy to use.