|GAJ in action...|
It depends, for instance say that your wife asked you ..."Man what the heck were you doing with your computer around 2pm yesterday?, no lies!" :P. And being a brain-damaged geek you couldn't possibly remember what you were doing at that time, wouldn't it be nice if you could remember it (only things that you were doing using the PC of course).
If you had GAJ installed, then all you had to do was open it and simply navigate around "history" and Gnome Activity Journal would have an entry about the thing that you were doing at that time!. Savvy!.
Even if you have cleared the cache of your Web browser, etc still GAJ will have an entry, in this case, concerning your web browser's activities.
Importantly GAJ uses a technology called Zeitgeist, which actually is a software layer (framework) that has the ability to collect and "read" activities based of users thus makes "predictions" about what programs they like the most or what they could be doing as soon as they logged into the desktop at the starting of their day, etc.
Gnome activity journal runs on top of Zeitgeist technology, then store the data and even intelligently categorize them such as ...
*. Data type.
*. Location of use (GPS).
*. Bookmark your favorite "activities".
*. Search... are among few of the main feature.
If you haven't used this type of a Journal in a while, then it would take few minutes to get used to it. But being a Gnome app, it has a simple GUI and quite easy to get used to nonetheless.
If you use the Ubuntu 11.04 Natty Narwhal you can easily install Gnome activity journal 0.6 by entering the below command (using a PPA channel). Enjoy!.
sudo add-apt-repository ppa:zeitgeist/ppa
sudo apt-get update
sudo apt-get install zeitgeist gnome-activity-journal
Do not run GAJ as the root user because it raises security concern since it uses Zeitgeist (if someone breaks into your system then they can easily see your history, etc).