How do you track everything you know? Computers and mobile phones in turn have become external memory, however data is still fragmented, stored in different formats and usable in different programs.
While there are partial solutions to this issue, none seem to be all-encompassing enough.
For example, PIMs come close for communication and contacts, but it's hard to extend and customise them. You should be able to associate custom tags and key-value pairs with "documents"/entities. This goes straight into ontologies since the question how to model many kinds of relations will be a problem to deal with.
Lastly tracking all data only makes sense if there are reasonable search facilities and if exchange with other databases can be done with security in mind, especially if even metadata is sensitive.