Note: The Drupal 7 version of the erp module was never far enough along to release. The Drupal 8 version is in progress, and development is proceeding over at https://www.drupal.org/project/stratoserp.
Run a small business? ERP is a module set that gives Drupal the capability of replacing Quickbooks, MYOB or MYOB Retail Manager as a major part of your business operations.
The Drupal node system is leveraged to great advantage for all aspects of the module set, so that almost any other Drupal module can also be added to expand the power of the system.
ERP takes advantage of existing Drupal modules wherever possible, using Views, Gmap, Date and Calendar modules in particular.
The ERP module currently acts as the core of our small business, handling all aspects of it except tax reporting and employee payroll.
This is probably the best way to get started at the moment.