I saw a note this morning from Marc Smith saying goodbye to Microsoft Research after ten years. He has done some interesting work there. Here are a couple of images generated from his projects.
This first is from a project called NetScan and was generated back in 2003. It is a TreeMap showing the Usenet Newsgroup community where the area of each box is proportional to the number of authors in that group. See here for more details and a larger, less blurry image.
This image below is called an 'AuthorLine' and is a type of dual histogram time-series that has some interesting characteristics. It was taken from a paper called Visualizing the Activity of Individuals in Conversational Cyberspaces.