When Google hands over e-mail records to the government, it includes basic envelope information, or metadata, that reveals the names and e-mail addresses of senders and recipients in your account. The feds can then mine that information for patterns that might be useful in a law-enforcement investigation.
What kind of relationships do they see in an average account? Thanks to the researchers at the Massachusetts Institute of Technology Media Lab, now you can find out. They've developed a tool called Immersion that taps into your Gmail and displays the results as an interactive graphic. (That's mine, above.)
The chart depicts all of your contacts as nodes, and the gray lines between those nodes represent connections between people by e-mail. The larger the circle, the more prominent that person is in your digital life.
A word of warning for the privacy conscious: To use the service, you need to give MIT permission to analyze your e-mail metadata. Once you've done so, it'll take a few minutes to compile everything. When you're done, you're given the option to delete your metadata from MIT's servers.