CP,
Don't know if this will be helpful or if you're way ahead of this, but ...

In Filemaker data is easily ranked by creating a related file and displaying the required data in a portal, with the data sorted by a field that can be easily changed dynamically using a script. With the data sorted in the desired order, a script inserts the portal row number into the ranking field, and looped to run through a group of records. Exclusions can be easily accomodated with 'if' or 'case' statements.

The shortcoming of this is that it will give each line a ranking, even if the data is equal, but for me that is a small price for such ranking ease.