Personal analytics is indeed a very interesting topic (cool article from stephen wolfram: http://blog.stephenwolfram.com/2012/03/the-personal-analytic...).

The biggest challenge imo is privacy and security: How do you safely collect and process everything (from emails to texts)? While I could implement something for my personal use, would anyone give access to all their communications to a third-party service? I wouldn't.

Maybe there is some better way to collect this information (just metadata? do some analytics and store results instead of raw messages?).