Exporter for Contacts (was "Export Address Book") is a popular Mac app to export contact data from Address Book to EXCEL, CSV and other formats, capable of organizing export setups in customizable templates to make repeated exports a lot easier.
The app lets you export selected contacts, groups and whole address books.
It lets you decide which contact fields will be exported and in what order.
You can export your Contacts and insert them in FileMaker.
Also look at : http://www.scoop.it/t/learning-filemaker?q=contact+export
and http://www.productivecomputing.com/address-book-integration if you want a full bi-directional tool.