Bake alternate UV data to additional texture maps
Being able to bake additional UV channels into a texture that can be used to generate flow maps, uv texture maps and other methods of distorting a texture to fit a UV map of a mesh. For a detailed description of a different use of this, read: http://www.valvesoftware.com/publications/2011/gdc2011grimesnonstandardtextures.pdf
They go into the shader side implementation of these ideas, but some do apply to Substance rendering too. It has similarities to Tri-Planar shading, where other data is used to map textures to a mesh.