Thanks so much for the quick response.
Your pointer to bulk operations, " Bulk Tag All Topics Based on a Keyword", is very helpful. And I will use it. To really implement my feature request, however, I would need access to the array of watched words and the tags they are mapped to, so I could loop over them and assign the tags. Probably these are available in the rails console? Maybe there is documentation somewhere for what system variables are available on the console? I tried searching a bit in the sysadmin category; no joy so far.