Requested feature:
Add a 'last tagged' column to https://e621.net/tag/index, to show the most recent date when the tag has been used.

Why would it be useful?
Being able to easily spot tags that have gone unused for months or years would be useful for finding ones that might need clean up. Could also be useful for alias/implication/invalidation debates.

Also, maybe this could eventually be used to wipe old defunct tags from the database. There's currently over 15000 empty tags; I'm thinking that those could use some automatic pruning.

What part(s) of the site page(s) are affected?
https://e621.net/tag/index

I think this one would require additional data in the database, because most recent date when the tag has been used is probably not stored, while most recent image the tag is used on would be trivial to get.

Suggestions that involve adding more columns in the database are tougher sells because of the performance hits.

Lance_Armstrong said:
I think this one would require additional data in the database, because most recent date when the tag has been used is probably not stored, while most recent image the tag is used on would be trivial to get.

We used to have a tag cloud feature that was able to show all the tags added on specified day/week/month: https://e621.net/tag/cloud. It was disabled last year, when the site was having performance issues. But if it was possible to retrieve that from the database back then, it's probably still possible.