If its your blog you can install plugins like:

 - [PDF24 Articles To PDF][1]
 - [Kalin's PDF Creation Station][2]

that alow creations of PDF from your posts/pages.
And if you are just reading that blog you can use one of many url to pdf services like http://www.pdfonfly.com/


  [1]: http://wordpress.org/extend/plugins/pdf24-posts-to-pdf/
  [2]: http://wordpress.org/extend/plugins/kalins-pdf-creation-station/