If you are using gMail and ever wondered what your usage is really like, check out gMail Meter.
What does this do? Well, it may help you change your email habits by showing your patterns.
The link from LifeHacker is here
You create a new spreadsheet in Google Docs, name it Gmail Meter and then run a script from the Script Gallery.
Then let the script run. It can take a while to run but you can just let it go, it will send you an email when it's done with all of the stats. What kind of stats? Here's just a smattering of the stats: