This was something I saw on another website, well, a friend pointed me towards it, and I thought it'd be a nice challenge to copy it.
So I copied it. The idea/feature is the grey bar at the back which moves towards the current button.
I really don't like it. It makes the navigation feel unresponsive, even though it works exactly as I want it to. It doesn't really add much value to the navigation either, its simply a visual key that builds on flash's power, but with no point.
The code I created is quite dururable, you can download the source by following this link:
Note: (The font got messed up, I forgot to export the correct one with the movie)