Pick an object (or make your own), pick its mass, and hit space. The Numbers are so big because it treats a pixel as one meter.
For those who don't know what Moment of Inertia is: Inertia is an object's resistance to acceleration. For movement in a straight line, it's always equal to mass. Newton said that F = ma, so if 'm' (mass) increases, 'F' (force) must also increase to keep 'a' (acceleration) constant. For rotation around an axis, it's more complicated, and the shape of the object comes into account. In science class, we had to look at a table of which shapes mean which numbers. PFFT! Who needs that? This thing finds it for any shape anywhere! ...also there's a smart person way to do this, but as of the making of this thing I don't know calculus yet.