KYou, a new open source solution to know yourself better
frankrousseau.github.io
frankrousseau.github.io
[edit]: Cozy is a self-hosted web application (similar to ownCloud) so you're sharing the data with yourself. My point about browsing history and application usage still stands.
About six months ago I wrote an OS X app (and browser extension) that tracked all my computer usage. It never grew past a prototype, but I'm thinking of starting work on it again.
It's ObjC and not python, but you might be interested in this -- https://github.com/andrewschleifer/Slife