Since Enron is in the news again, Trampoline Systems have produced an Enron Explorer that lets you sort through the emails, even getting down to the raw emails themselves. Trampoline offer software to do this within organizations, and the Enron data is a nice example dataset to show off the technology.
The central aspect of this analysis is the connection between people, themes and the underlying raw data (email). I particularly like the "tag cloud" look to the related themes and people panels, which gives you a quick overview of topics covered. Given that this is a network visualization, there is a tool for visualization of the people connections. It lets you traverse nodes to see people's extended networks.
Trampoline's description of this tool
In October 2003 the US Federal Energy Regulatory Commission placed 200,000 of Enron's internal emails from 1999-2002 into the public domain as part of its ongoing investigations. The archive offers an extraordinary window into the lives and preoccupations of Enron's top executives during a turbulent period. Read more about Enron's demise on Wikipedia.
Trampoline engineers used this data as testbed during development of the company's SONAR technology. The result was so fascinating we decided to open it up and allow anyone to dig in. The Enron Explorer lets you investigate the actions and reactions of Enron's senior management team as the noose began to tighten.
A number of people have played with the publicly-available dataset of Enron emails to do social network analysis, such as the work of Jeffrey Heer.