This project has been stalled, I will not continue working on it!
Basic concept:
The idea is to have a 16mm vandal button like this:

But with 12 RGB LEDs inside that can be controlled via USB. The button would be connected to a USB2.0 header on the mainboard. Secondary features are that it doesn't need soldering and that the cables exit towards the side. It will also have an input for the HDD LED and you could use it as a reset switch as well.
Try out the online Visualizer 0.2 here!

Uses:
Possible uses for these LEDs would be customisable ring colour, a ring loading animation whenever there's HDD activity, multiple segments lighting up the more controllers are connected (like the Xbox 360 did), a simple clock, a breathing LED animation when the PC is sleeping, rainbow colour gradient animations, you name it.
Ideas:
What would extend the possible uses is if one could also read the button via USB, so if you installed multiple switches they could open a program, disable WiFi or whatever. Another idea is to allow the HDD-LED input to be used as an output for other LEDs, so if you installed the switch alongside an existing front-panel, you could control one of its LEDs as well.