Control iMac and LED Cinema Display Brightness Simultaneously

I have a iMac 27'' and a LED Cinema Display 27'' connected to it. And I've noticed that to be able to control brightness I need to open the Display.prefPanel and modify the brightness of the displays **individualy**. Is there a way to do this **simultaneously**? Maybe with a third party app? If not, is there a way to assign a keyboard shortcut to the second display brightness?