LED Activity for Raspberry / Cubie

I made a couple of Volumio base player (in Raspy, Cubietruck, Raspy 2) - all works fine, but there is a one problem.
It will be very useful to have one simple LED (mounted on the front panel) for control running (activity) of computer. Not “Power On”, but “Activity” (because comp may be freez, or not start after “Power On” - in this case such LED will be very usefull for control the situation.
May be somebody know, what pins of Raspy and / or Cubie can be using for connect this LED (without any software manipulation)?