Dubsmash - From silly lip-syncing to full featured video messaging 😜
John's Background Switcher - Switch backgrounds to trending imgur, reddit, tumblr threads
SE Ranking - All-in-One cloud-based SEO software for agencies, marketing teams and webmasters
Variety Wallpaper Changer - Variety is a wallpaper changer for Ubuntu which is featureful, yet slim and very easy to use.
JibJab App - Add your self(ie) to hilarious animated GIFs and messages!
Muzei - Muzei is a live wallpaper that gently refreshes your home screen each day with famous works of art.