Where Does my Tweet Go? [wheredoesmytweetgo.com] provides an original 2D or 3D view revealing the reach of individual tweet messages over Twitter's social network.
The line graph at the bottom shows the number of retweets and the actual reach of the message, itself shown in the center, over time. The circular graph conveys the number of retweets (with blue lines reaching consecutive concentric circles depicting the degree of retweeting) as well as the number of people the message actually reached (length of the 3D green lines).
See also NYTLabs Cascade: How Information Propagates through Social Media for another 3D depiction with similar goals.