Just some notes on what to modify in robots.txt file on an Drupal installation when using some modules like print, and AddThis. Disallow print, printmail, and bookmark.php. I always using clean URL:s, so I never change values in the last section.
This describes two modifications I have done to my sites Fivestar module. The first thing is to avoid indexing of words describing the rate levels "Star labels", like "Poor", "OK", "Good" and so on. While you are there you can always add relation attribute to avoid unnecessary follow of the rate link.
The second thing to do is to add comment tag to avoid AdSense analysing "Star labels" as content.