When the $275 billion American Recovery and Reinvestment Act went into effect, Congress required that states receiving the money set up websites that would detail how the money was being spent. There was talk of thousands of "citizen IGs" monitoring that the transactions would be honest and aboveboard.
Well, it turns out that those citizen IGs never materialized, and yet the ARRA had remarkably little waste, fraud, and abuse. The IBM Center for the Business of Government, which does a bang-up job analyzing government activities across the board, studied the websites in six states where the spending was detailed (all states did it, the group chose just six as representatives).
The report concluded that because the states had to think about what they were reporting, they developed a better understanding of what was going on in their own states -- and thus a better understanding of how ARRA was helping. Which once again proves that if you measure it, you do it better.
The IBM report, Recovery Act Transparency: Learning from the Experience of States, is available free, as are the IBM center's other in-depth and probing reports.