The recent years have seen the emergence of a number of virtual worlds with various designs and purposes. Some have become very popular and have developed growing in-world economies. Real-world businesses are increasingly experimenting with doing virtual business there as well. In this paper, we present Avatar Business Value Analysis, a novel theoretical framework and a computational method and decision tool to help evaluate and strategically manage business value creation inside synthetic environments, and show how it can be applied to cost-benefit analysis in practical settings. The decision-tree-based method includes traffic metrics that may be used to empirically estimate the business value of virtual commerce ventures. We also investigate some intangible factors that are impacting these metrics in the context of the particular case of the virtual world Second Life and discuss their implications. We conclude by outlining strategies that could be considered by the operators of virtual worlds and the real corporations in order to promote sustainable virtual business in synthetic environments.