Mihai Parparita, a Google developer, has created a system to display information about your email over time. Mail Trends is a python script that connects to your Gmail account through IMAP, and generates a series of tables and graphs showing information about your mail account over time. The time aspect is key, it's one of the most interesting parts of email, and something that distinguishes it from other implicit data we have access to. He has a demonstration using part of the Enron data set, and you can see the most prolific emailers, subjects and who sends you the most email. I was hoping it would also demonstrate searching by keyword, since being able to look for specific terms is very useful for research in Google Trends and similar buzz tracking sites for the web. One of my goals is to both show graphs of search keywords over time in your mail, in the same way that MarkMail does for its public mailing list search, and also have a animated tag clouds that show the most popular terms as they change over time. I'll be watching closely for future developments, at least one of the blog commenters understands how this could build into something larger.
On the technical side, using IMAP is a great way to work around the lack of a proper Gmail API. He's using the Python IMAPLib, I'll have to look at the equivalents for other languages, since I have an irrational prejudice against any language in which whitespace is significant. Tabs in make files also bother me, but I've learnt to live with them. A hat tip to Brad and Googlified for pointing me towards Mail Trends.