Way to show changes to a particular node to users
You could try Revisioning (integrates with Diff) for both Drupal 7, and Drupal 6.


  Revisioning is a module for the configuration of workflows to create, moderate and publish content revisions. You use it in scenario's like this:
  
  
  Authors write content that prior to being made publicly visible must be reviewed (and possibly edited) by moderators. Once the moderators have published the content, authors should be prevented from modifying it while “live”, but they should be able to submit new revisions to their moderators.
  We shouldn't have to grant these roles “god-like” powers (e.g. Drupal 6's "administer nodes" permission) to implement this.