New field for additional url variables when creating/modifying an FU that uses a redirect.
Example: Adding the following data to an FU redirects for SEO tracking:
Currently the only way to achieve this solution is to create empty nav nodes with external redirects (which redirect internally, but allow you to add url vars). You still have to go to the original nav node and create the FUs. A messy and complicated process. Managing the data is even messier and clients forget the process.
The solution proposed above could make it very simple for the content editor by just adding the new field to the FU.