Visualizing.org has a neat twitter visualization online of 1645 twitter accounts related to information visualization.  Taking a short list of seed accounts and then finding all their followers and friends, the result is an impressive (if not a bit crowded) graph visualization.  Some edge bundling would have been nice, but you can get a rough idea of the connectivity just from the sheer number of connections.

I’m proud to see @VizWorld on the map as a rather prominent bubble near the upper-right area.

Visualizing.org Player | visualizing.org.