cck (embed in the kernal in drupal 7)
The Content Construction Kit allows you to add custom fields to nodes using a web browser.
views
Among other things, Views can be used to generate reports, create summaries, and display collections of images and other content.
panels
The Panels module allows a site administrator to create customized layouts for multiple uses. At its core it is a drag and drop content manager that lets you visually design a layout and place content within that layout. Integration with other systems allows you to create nodes that use this, landing pages that use this, and even override system pages such as taxonomy and the node page so that you can customize the layout of your site with very fine grained permissions.
context
Think of conditions as a set of rules that are checked during page load to see what context is active. Any reactions that are associated with active contexts are then fired.
pathauto
The Pathauto module automatically generates path aliases for various kinds of content (nodes, categories, users) without requiring the user to manually specify the path alias. This allows you to get aliases like /category/my-node-title.html instead of /node/123. The aliases are based upon a "pattern" system which the administrator can control.
Tagging
Used to handle the tag taxonomy.
i18n (internationalization)
Language selection (when you switch the site language you'll see only the content for that language)