I had written a Gmail gadget that lets you track your usage of gmail. The tracking data was stored inside your own Google Calendar. The calendar was also used to send SMS messages if anomalies were detected in logging into the account.
The only think the gadget seemed to lack was visualization. I wanted to use Google visualization some day, but could never find enough time to get it done. That is when I decided to piggy back on the visualization capabilities that bit.ly provides. I had written about the way to track rogue visitors. The same scheme can be applied to this Gadget also.
An extra link was added at the bottom of the gadget where the user can specify the bit.ly URL. This is saved as a user preference and an invisible image with this link is appended everytime the gadget is loaded. Since a call is made to the bit.ly url, the access is tracked. The code is now uploaded to http:\\gmailids.appspot.com. The source code is also available here. To enable this change, you may have to add the gadget again (which may result in losing the existing data about how long you have spent on gmail), or when Gmail picks up the data.