From Productive Computing:
The FM Books Connector plug-in provides FileMaker Pro access to every available record stored in a QuickBooks company file. Using this plug-in you can freely and easily exchange data between these two powerful applications. It allows you to populate QuickBooks with FileMaker data, and extract data from QuickBooks into FileMaker. It does not require knowledge of XML, communicates with all available QuickBooks Tables, Records, and Fields. It also includes demo file and detailed documentation, online tutorial videos for coding examples.