xTuple PostBooks accounting, CRM, and ERP for Mac

From xTuple:

PostBooks is the free and open source ERP solution from xTuple. It is built with open source technologies such as the PostgreSQL database, and both the server and the graphical client run on Windows, Mac, and Linux. PostBooks features a fully integrated accounting system (A/R, A/P, and General Ledger), as well as CRM, Sales, Product Definition, Inventory, Purchasing, Manufacturing, and Distribution. It also features a fully integrated copy of the OpenRPT report writer. It is the ideal solution for the startup businesses expecting rapid growth, or growing businesses looking to make the step up from desktop accounting software.