A couple interesting apps. May come in handy if we ever want to actually draw pictures of all this stuff:
The Social Collider
A web service that creates a visual map for any Twitter account of the other accounts it is most frequently used to converse with. The site uses the Mailana social network analysis system to analyze Twitter conversations and come up with the data for the visualization.
Marshall Kirkpatrick recently used the Top Twitter Friends web application to generate an analysis of a series of popular twitterers, complete with lists of each Twitterer's most frequently contacted friends, and a screenshot of their visualization. Marshall's perspective is that the openness of this information gives us some pretty intimate insight into the inner circle of influential people in our social networks, and those of notable people.
Not only can you see who people most frequently converse with, but clicking the info link beside a person's account name reveals a tag cloud of the most commonly used words in the conversations between the two Twitter accounts in question, plus an additional link to actually go and read the conversations between them.