Ask HN: Has anyone done anything interesting with Email Analytics?

It feels like there's a great start-up that could simply analyse my email and offer me certain data that would be insightful. For example: Who do I email most without receiving a reply? Who am I worst at responding to? When do I send the majority of my mails etc.

Even if restricted to work with GMail.com this would still be killer.

Anyone know anything in the area?