I just released the 7th beta of Ah3, it now offers documentation for most features and seesm to be relatively stable.

Ah3 is an invoicing and inventory system for repair shops. It comes configured for an auto repair shop but can be configured to handle any shop with customers who have things to be repaired. It includes a customer and vehicle database, the ability to generate invoices, and the ability to track the repair history of a vehicle. It also tracks inventory, allowing for parts with multiple vendors and costs and other information.

You can learn more about it at http://www.linuxlots.com/~ah3