There are thousands of contributed Drupal modules on Drupal.org, so it may be tough to find the right Drupal module for what you need to accomplish in your Drupal project. This can be especially frustrating if you are new to Drupal and aren't sure what you are supposed to be looking for. Below I have compiled a list of the top 100 Drupal modules according to usage statistics from Drupal.org. This should give you a solid list of Drupal modules to get started with.
Our Top modules list has grown to over 100 modules at this point, so if you are looking for more modules specific to your version of Drupal, please check out the Drupal 6 modules and Drupal 7 modules pages. There you can find more information on Drupal modules specific to your version of Drupal.
Drupal Modules are the core building blocks to a great website using the Drupal CMS. They are essentially addons, or plugins to the core Drupal CMS technology. Drupal's core is actually just made up of modules that eventually are comitted to the core software system. There is a huge community behind the development of these modules and they range from very simple to very complex in their functions. We will do our best to provide you with some great modules that every Drupal server admin should have in their toolbox, and a ton of others that can add new functions to your site in a few simple steps. See our Drupal module installation tutorial if you are unsure how to install any of these modules.
This is only the tip of the Drupal module iceberg, as there are over 3000 contributed Drupal modules all together. These top 100 Drupal modules will give you the ability to create some very powerful websites with Drupal. If none of these modules give you the funcationality you need, you may want to check out some of the newer Drupal modules that aren't making such big waves yet. We are always adding more new Drupal modules as the community is always coming up with bigger and better modules.
If you can't find any contributed modules that accomplish what you need, then you may need to have a custom module developed.