Cuboo sent me this example of dashboard used in a bank.
It shows how Piecharts (damn piecharts) can be used as a signal.
Here it comes to red, when actual stock is lower than stock at the beginning of the year.
For those of you who speak German, have a look at his site : http://openbi.info/
Here goes another one from AC for web traffic analysis, using bulletcharts, linecharts and variancecharts