This is a neat little trick. Like quite a few things on your Mac the cool features are hidden away. Although this tricks is rather simple it is fun to do. As well as this there is quite a lot of detail to be had by looking through the files (which I think are written in some form of C).
The first step is to open up Terminal. No hidden feature would be without good old Terminal. Anyway change the directory to the following:
The next step is to view all of the files in the folder. Type the list command to view the available commands. Type the following into Terminal. You should see some results similar to the image below.
The next step is to view these files. Simply type the following. You can replace any name with the ones you have in your list.
This will give you a long list of interesting dates. Unfortunately the all calendar doesn’t seem to show every file. But you can use the following to achieve a similar effect.
Simple, interesting, but its uses are pretty limited. I don’t know a way in which you can import them into iCal, although you probably wouldn’t want to since most of them are in the past.