Tagging all assets in a sub directory
Seems doable with a custom plugin.

The pseudo-code would be something like:


Use AssetsService to grab all of the files for the source.
Loop through the files and parse the parent folder paths.
Based on the subfolder for the asset, check if an existing tag already exists with the TagsService.
If 3 is true, assign that tag's value to a tag field on the Asset.
If 3 is false, create the tag using the TagsService, then assign that tag's value to a tag field on the Asset.