Lots of people think of Drupal as just a content management platform or a social networking application framework. However, UberCart features are getting more and more extensive these days that Drupal can be a full featured online and offline commerce system. Most of us know about the basic features of UberCart such as the credit card payment gateway, the shopping cart and the shipping modules. However, UberCart can also become an amazing POS system for offline/over-the-counter purchases. All of this is made available with the UberPOS module. The module runs on Drupal 6.0 and requires Ubercart 2.0.
We are currently using this module for a pharmaceutical products ecommerce system. The users of the site utilize UberPOS for offline/in-store purchases. In such a way, both offline and online purchases are processed by 1 system. UberPOS can be hooked up to credit card readers and cash registers. You can see a full list of supported hardware here: http://uberpos.com/page/hardware-tested-uberpos
In such a way, UberPOS becomes a full featured POS system.
For more information about UberPOS, you can go here: http://www.uberpos.com/