This application allowes the user to change wallpapers on his/her phone. You can push wallpapers from your computer to an online WebApi which is access by the phone application. The source code of the API is in tkoppop/Andriod-Wallpaper-Engine-API.
What the code does: This is just a simple website coded in javascript. You set a name for the wallpaper, use the key "tkoppop@Wallpaper@Test@App", then you upload a thumbnail, and then the actual image.