If you want to find out which sites someone's been accessing on your PC then you've always been able to check their cookies folder, which generally provides a few clues (the domain name, basically).
Google Analytics cookies can provide extra details, though, including the search keywords used to find a site, the number of times a site has been visited, and the date and time of the last two visits. Intrigued? The Google Analytics Cookie Cruncher can tell you more.
Launch the program and you must first choose the browser you'd like to examine (there's support for IE, Firefox, Chrome and Safari).
Next, point Google Analytics Cookie Cruncher at the folder containing your browser's cookies (a Help pane offers useful clues).
Finally, choose a folder for your reports, click Process, and that's it: within a moment or two the program will have processed your cookies and created several CSV files with whatever browser activity details it's found.
There are several usability issues here. It's annoying that you have to manually browse to the default cookie folder each time, for instance (the program already knows where this is, it should at least start at that location). And ideally it should display the cookies first, rather than just dumping them to a file and assuming you have a suitable viewer to hand.
If you just want to find out more about what someone's doing online, though, Google Analytics Cookie Cruncher could prove very useful, and there's certainly more than enough power here to justify the tiny download.
An interesting tool which helps to show just how Google Analytics can track your activities online