Nis,
To understand how categories can help you, it's easier to give us an example of what it is you are trying to achieve. On a more general note. If you have specific interests or tasks, you you put them in a category box. You only set this up once, for each task you have in mind, and you can simply (hyper)link the categories to a number of individual packages and features, instead of repeating that process.
Questions, drop me a note.
Ben