Is there a way to track or record users entered taxonomy?
You may want to take a look at the Community Tags project.  We have used it on a few sites.  From the project page:


  The Module has three main features:
  1. Stores who tagged what and when.
  2. Allows for this information to be exposed with views.
  3. Adds an easy AJAX interface for tagging nodes without going to node/edit.