ActionScript 3.0 :: Capturing Clicked Item In Sort Of Variable?

With a simple array, I'm putting 7 instances of a movieclip up on stage like this:
ActionScript Code:
for (var i:uint = 0; i < 7; i++){
thing[i] = new Thing;
addChild(thing[i]);
etc;
}

This is all good. I'm essentially looking to capture which 'Thing' is clicked on in some sort of variable. Currently I am using getChildIndex to get a number:
thingClicked = getChildIndex(event.currentTarget as DisplayObject);
Which gives me a reference I can use later, but this is not ideal, as the number naturally changes whenever I add others stuff to the stage.