David K. Levine has written a white paper for the NSF proposing that they invest in large-scale simulated economies as virtual laboratories:

An alternative method of validating theories is through the use of entirely artificial economies. To give an example, imagine a virtual world – something like Second Life, say – populated by virtual robots designed to mimic human behavior. A good theory ought to be able to predict outcomes in such a virtual world. Moreover, such an environment would offer enormous advantages: complete control – for example, over risk aversion and social preferences; independence from well-meant but irrelevant human subjects “protections”; and great speed in creating economies and validating theories. If we were to look at the physical sciences, we would see the large computer models used in testing nuclear weapons as a possible analogy. In the economic setting the great advantage of such artificial economies is the ability to deal with heterogeneity, with small frictions, and with expectations that are backward looking rather than determined in equilibrium. These are difficult or impractical to combine in existing calibrations or Monte Carlo simulations.