I'm sorry I couldn't think of a witty title.
I've been helping a lot recently with the ongoing tag clean up and I had a couple of ideas on how how to help further and speed up the process.
Firstly, with the help of @BenN, we have got a list of deprecated tags. Ben kindly made this query to find tags that have been marked for removal. This might be handy to collate the tags that have been forgotten about in one place.
The current list is as follows:
Secondly I made a query to find any posts in the First Posts Review queue that have these tags against them. My reasoning being that it helps keep the queue down and we can educate the users about proper tags right away.
Sadly the output of this data is not as immediately user friendly as it could be. If you copy the ReviewID number and append it to the url
https://superuser.com/review/first-posts/ you can jump straight to that review.
I hope this helps you out and feel free to copy it to other sites if you think it would help them with their pesky tag problem. Again massive thanks to @BenN for helping with the queries and pointing me to the data.SE site in the first place.