"Zeitgeist logs user's activities and notifications (files opened, websites visited, conversations hold with other people, etc.) and makes the relevant information available to other applications". Starting with Ubuntu 11.04, Zeitgeist is installed by default in Ubuntu and is used by the new Unity menu called "Dash" (Applications / Files Places) as well as other applications such as Synapse, Sezen, Avant Window Navigator, DockBarX, Docky, Cairo Dock, Gnome Activity Journal and more. It will also be used in Gnome Shell.

Activity Log Manager lets you delete part of the Zeitgeist history, blacklist some applications or prevent logging certain types of files as well as blacklist folders. This is useful if you want to keep some recent files from showing up in Dash (in Unity) or maybe just to exclude some private files or folders and so on.

(Deleting Zeitgeist history)