Question: Is there some way to tell who has created which tags, and when? If a method doesn't exist I would petition SO to add this, as I would very much enjoy seeing tags I created being used by other people. 

SO must track creator meta-data on tags since a badge is awarded for creating a tag used by 50+ questions (taxidermist).

Answer: 
One does not.... Maybe the data dumps... But this is not visible at this time as far as I know...
This is now covered by the **Taxonomist** badge.

To see a list of all those with the badge and what tag they created (so long as it is still in use), check out the [Taxonomist](https://webmasters.stackexchange.com/badges/11/taxonomist "putting tags in your skin so you can eat while you freak") badge page.

To see what you alone created, check out the bottom portion of your user profile.