Dynamic Metadata

I've poked around in the forums and haven't been able to find exactly what I'm looking for, if it's possible at all.

I'm looking for a way to dynamically add/change metadata based on a specific field.

For example, I'd like to populate tag values and a number of custom columns based on the value in the Series field. This would be after the books are added to Calibre, during the "polishing" process.