Where's The Debt Going?

I have posted various debt statistics before, but perhaps the single most troubling one is that of debt intensity of economic growth, i.e. how much additional debt is taken on to generate one more dollar of GDP (see chart below - click to enlarge).

US Debt Intensity of GDP Growth

It now takes roughly 5 dollars of new debt to generate 1 more dollar of GDP. In gross dollar terms, during 2006 total debt grew by $3.55 trillion whereas GDP grew by just $0.79 trillion. Notice how GDP growth in dollar terms has been stuck in the same place for 4 years running, whereas debt growth has moved steadily upwards.

Which begs the question: where does all this added debt go, since it does not get consumed or invested in plant and equipment (it would have shown up as GDP growth)? And what are the final consequences if this imbalance keeps going on? These are truly not easy questions, so I will leave them open for your comments...

P.S. There are no singular "correct" answers. There is the "easy" Ponzi answer, i.e. issuing more debt to pay interest on existing debt, but I think there are more elements at play here, particularly in the nature of the debt itself (e.g. financial vs. non-financial in origin).