Download post as text file
try the views_data_export ....  it can export to CSV or basic text format. and you could select a users Nodes: title and body at least ... and any other fields you want...


  This module is designed to provide a way to export large amounts of
  data from views. It provides a display plugin that can rendered
  progressively in a batch. Style plugins are included that support
  exporting in the following types:
  
  CSV
  
  Microsoft XLS
  
  Microsoft DOC
  
  Basic TXT
  
  XML