I had a fun idea to generate an image from html and css and set that image as the wallpaper all in Node.js. But why stop there? I built a HTML and CSS clock that got its time set with Javascript and had Node generate an image from that onto the wallpaper every minute.
The Code: https://github.com/danba340/wallpaper...
You can get this to run automatically when your computer boots using pm2. Instructions are in the README.md in the linked Github repo.
Say hi on twitter: / barelydaniel