Apparently this functionality has been there for quite a while, but I only chanced upon it recently.
Microcharts are not only an awesome way of displaying tons of data in a meaningful way, but they can also be used as a tree view selector. Try to imagine how would it be to use a combination of drop down selectors (each in its own panel, with complex targeting), and you will see why the tree view is so much better.

Here is how to do it:

The tree view can have up to three levels, which means you can have a total of three attributes before the dummy one. You need a dummy attribute (can be Year, or whatever) and a couple of dummy metrics, in order to have the widget render.
You also have to use one of the attributes (preferably the lowest grain) as a selector for other panels.

Have fun with it!
Sorin