I started using Metric Junkie as a way to track the rank history of my own books. It's straight-forward and it's easy to organize items to track. But Metric Junkie could be ultimately applied to a much more important mission. If we can track what people are reading, it tells us something about what interests them, what problems they are dealing with and changes they might want to make in their lives. If you know people are buying more books about building homes, getting out of debt or about changing careers, this can be a leading indicator of major trends. This is part of my research for my next book and Metric Junkie makes it possible.