If you want to learn a little about our economic history of the past 100 years, I can't recommend this series enough: The Commanding Heights. This documentary will take you through the various economic philosophies that have dominated the international environment since the turn of the last century. Interviews with Hayek, Friedman, deSoto, and several world leaders make this an excellent series.
The Bureau of Economic Analysis: http://www.bea.gov/. Here's where you get all that great data on US GDP and so forth.
Here's a Wiki list of countries by national debt: http://en.wikipedia.org/wiki/List_of_countries_by_public_debt.
Items of interest for those with nothing better to do:
Understanding the Solow Growth Model, a working Mathcad illustration: Solow Growth Model. And for those without Mathcad, a PDF: Solow Growth Model PDF.
Understanding the Diamond Growth Model, a Mathcad illustration: Diamond Growth Model. And, again, for those without Mathcad, a PDF: Diamond Growth Model PDF.