Last.fm has (or had) something similar and quite sexy as well:
http://blog.last.fm/2008/08/01/quality-control
My favorite feature was hooking it up to loudspeakers and playing a particular sound from their game every time the business made money, with the sound corresponding to how much money they made.
They eventually disabled it, because the constant interruptions were starting to annoy people. This is a nice problem to have.
http://github.com/russss/arduino-gauges
I also helped out with the analogue tweet-o-meter from a couple of weeks ago: