I was hoping to use the APIs to discover the number of questions for a given Tag as well as the number of followers.  I found how to get the number of questions, but not the number of followers.  On stackoverflow, if you hover your mouse over a Tag a DHTML popup displays the number of followers for that tag.  I have used the stacksapps search as well as Google and can't find this piece of data in the APIs.  Am I missing something?  If "followers" is not a discoverable piece of data, consider this a feature request.  :)