Drupal gives you the possibility to add a taxonomy which makes it possible to add keywords to an article/page so users can click on these keywords to find related content. See www.softwaremagazines.com on how this looks at the front-end.

To add a taxonomy do the following:

1. Click on Administer
2. Go to Categories
3. Add vocabulary (f.e. keyword)
4. Select the pages on which you want to add this feature (blog/page/story)
5. Select if you would like to allow a three-like hierarchy
6. Select the other options
7. Save and the taxonomy is activated

Now you will find an extra field if you create content. This field is displayed below the title and as soon as you're entering keywords overhere they will be saved in the list terms in this category. So you can maintain the keywords which are created via Categorie / list terms.