The Drupal Taxonomy module automatically provides a tag specific RSS feed.

For example, the tag term "Drupal CMS" has a tag ID ("tid") of "49", and the following URL auomatically creates a feed that shows any new post that contains the term Drupal, such as:

http://www.mcaudy.net/drupalflexLJ/taxonomy/term/49/0/feed

Adding this feed link to your feed reader will allow see when any posts have been added that are tagged as "Drupal" related, and clicking on the link will take you to those posts within DrupalFlex.