Modules add features to Drupal. They are free and there's no limit to what you can do!
https://drupal.org/project/modules
Lesser Known Modules I've Used
This article lists unique Drupal modules used for specific client needs, such as customizing date formats, synchronizing custom blocks, and managing field dependencies. It highlights their functionality and includes links for further exploration. Addition
Read more: Lesser Known Modules I've Used 
The Redirect Module
Read more: The Redirect Module
The Webform Module in Drupal
Read more: The Webform Module in Drupal
The Feeds Tamper Module
Read more: The Feeds Tamper Module