David Roodman has a superb graphical visualization of the cross-border flow patterns of over 4.3 million different types of microloans - education, health, food, agriculture, retailing etc - channeled through Kiva, the ostensibly person-to-person microlending site.
The graphical illustration is stunning in its ability to convey the emergent dynamics of such activities. The flow patterns show how the numbers of lenders and borrowers build-up with time. Once a small trigger initiates the flow, (presumably) demonstration effects tap into latent demand among the massive pool of borrowers and generates confidence among lenders. It is also an excellent illustration of how social systems develop and the importance of initial patterns in consolidating the final outcomes.
The borrowers are concentrated in West Africa, Kenya, Latin America, Peru, Chile, Philippines, Indonesia, and parts of Eastern Europe whereas the lenders mainly come from US, West Europe, Australia and Japan.
On a more general note, I believe that a lot of complex public policy challenges can be more effectively communicated using vidualization graphics. For example, a time series trajectory of visuals of an area can highlight how specific infrastructure or other interventions there impacted the area's development in a cognitively striking manner. In fact, such visualization can beautifully capture the emergent dynamics of social and economic systems in response to specific triggers.