Here are a few drupal modules built and maintained by the community that seem quite useful. Thanks to all the folks who have spent time and energy maintaining and releasing these modules. Note that most of the project descriptions have been lifted from the project page on Drupal. If you have questions or bugs related to the below modules, please file them on the issue page of each module.

• CiviCRM Subscribe: Allows users to subscribe (double opt-in) to a CiviCRM group without creating a Drupal user.
• CiviCRM Active User: Adds a user to a group upon Drupal login. Not only must the user signup for a CiviCRM group, they must use their Drupal login by signing in at least once.
• CiviCRM Theme: This module extends the Drupal admin theme page options (admin/settings/admin) to allow settings of custom CiviCRM user and admin themes.
• Organic Groups CiviCRM: The OG_CiviCRM module integrates organic groups with CiviCRM groups. This is useful for groups that form organically on the web but need to be tracked for an organization. Note that this module is looking for funding to be upgraded to the latest versions of Drupal, OG and CiviCRM.
• CiviCRM Error: Sometimes CiviCRM can be real tough to debug. Especially when you are getting fatal errors, but only by some users, and you can't recreate the problems. This module will send you a detailed email when a CiviCRM fatal error occurs.
• CiviNode: CiviNode is a module and API that exposes CiviCRM contacts, groups, and other CiviCRM object types to Drupal as nodes. It's designed to make CiviCRM easier to use and integrate with all of the Drupal tools and techniques you've come to know and love.

If there are other modules that should be listed above, please let me know. Please do help and contribute back to the development of the above modules in any way you can (documentation, testing, debugging, financial etc). Note that we have not tested or worked with most of the modules above, BUT we have worked with the authors of the modules above. Please do your research before you decide to use the above modules.