The Drupal core contact module provides a no-frills way for users to email you via a simple webform. If you like that module, but would also like those form submissions to be recorded in CiviCRM, then this no-frills extension is for you.
This module will record an "inbound email" activity every time a user (logged-in or anonymous) sends a message via your site-wide contact form. If they do not already exist in CiviCRM, a new contact will be created.
There are no configuration options for this module. If you want more advanced features or options (such as collecting more info about the contact, adding them to groups, etc) consider the Webform CiviCRM Integration module as a much more robust solution for updating CiviCRM contacts via Drupal webforms.