Fineo is a web application by DensityDesign to create alluvial (Sankey-like) diagrams. I have been the principal developer and designer of the tool.
Fineo was born from the idea that Sankey diagrams, although developed as a technique for visualizing continuous data, may be used to represent relations between dimensions of categorical data. The application has been used as an analytical tool for the Mapping the Republic of Letters project at Stanford University.
Sankey diagrams are flow diagrams that represent flows of continuous data such as money, energy or material in a system. Fineo, instead of using the flows for this purpose applies them to represent relations between multidimensional categorical data. This use of sankey diagrams was first developed by DensityDesign as a static infographic on the DRM project. The infographic used only two categorical dimensions, but was the base on which Fineo's development started.
Recently the use of sankey diagrams for comparing couple of dimensions has become quite popular, even though it has never been formalized. From the DRM's experience we understood that the same concept may be applied to more dimensions and that we needed a software to automatically generate the visualization layout.
Read more about the project here.