That said, there is a lot to be gained by having copies of your personal email (and metadata) handy. I am sure I am not unique in that I've got a script that uses imap to pull non-spam email into a temporally ordered store (a DVD-R :-) and a dynamically updated index (initially sqlite, now its more mysql). Still lose stuff of course :-).
For those who can't code or don't have the time.
The landing page looks decent, I am not a fan of the mock conversation with Snowden, I think it is tacky. I see what you are attempting to portray however I think you miss the mark.
We need some more details rather than just telling us it runs on Google's App Engine.
I have built an Email Backup software for the Mac at http://thehorcrux.com/.
I'm currently building a cloud version of it at http://www.backupfog.com/.