This is my very first commercial piece of software, and it's a nopCommerce plugin that adds the functionality of a minimal help desk that features a knowledge base and a ticketing system. These features are designed to benefit the end customer, the merchant, and, perhaps, the people that provide deployment, customization, and integration services to merchants.

Other features include:

• Departments & agents management
• Ticket issues, statuses & reply templates management
• Articles, article feedback & category management
• Integration with activity log, multi-store support, customer role limitation
• Knowledge base & ticket creation directly in the admin area
• Anonymous tickets
  ... and so much more. 

You can check out the demo here. A playground is also available here, though it resets every three hours.

Supported versions: 4.50

Supporting new versions is my top priority, so if you don't see a version here, let me know.