On my desktop I use Xubuntu 12.04, and today i noticed that this distribution shipped by default the Zeitgeist daemon, a thing that I’m not using at all, for what i know.
Zeitgeist is a service which logs the users’s activities and events, anywhere from files opened to websites visited and conversations. It makes this information readily available for other applications to use in form of timelines and statistics. It is able to establish relationships between items based on similarity and usage patterns by applying data association algorithms such as “Winepi” and “A Priori”
Zeitgeist is the main engine and logic behind GNOME Activity Journal which is currently seen to become one of the main means of viewing and managing activities in GNOME version 3.0