While this specific project is a really neat back-lit bookcase with customizable LED lights galore, you could easily add the exact same setup to just about anything you wanted to give some LED love.
The core of the project is a set of addressable LED modules, an Arduino board, and a simple bit of code. You could use it to make a 70s style mood lighting box, add color changing accents to your media room, or any other number of fun projects just by cloning this project and extending/shortening the wires where appropriate. The control module allows for solid colors, multi-colors, and animations. Hit up the link below for more information including the source code.