provide a mechanism/interface to create extentions to manipulate tags (e.g. re-tag your collection)

I started thinking about this while suggesting allowing auto tagging based on file name or directory structure.

If there was such an interface, I could easily write a script to re-tag files based on their directory structure.

Other people could create extensions to re-tag based on whatever criteria they need.

Users could share their extension scripts so even non-technical users could use them. I am sure there would be a small comunity of extension developers but a large community of extension users.