Content Construction Kit is one of the most downloaded modules at drupal.org. The module is so populare that it's functionality will be buildt into the next Drupal release. If you need extra functionality, a new content type or need to modify existing ones, this module is a must. It's a good trick to know what you want before you install it, there are several cck-addon's and you can be confused at times. Take it easy, start with a simple text field and when you feel comfortable, go further.
