I've been giving this a lot of thought and at the moment, this is what I think I need:

• It should be a Today PlugIn.
• Store TDD (but make it optional since it is not an issue for everyone)
• Store number of days, with a default of 3 - use a Combo box
• Store information on the open task so it can be marked completed
• When the user clicks on the plug give the option to chose day or use given date, or ignore.
  • When selected the current open task is marked complete (but stays so that it can be tracked or deleted manually -- though this could be an option.)
  • A new task is created based on TDD and number of days, which ever results in smallest day.  However, TDD may be ignored.