Chris Hansen offers FX.php to get access from PHP to Filemaker [1]. There is some documentation around, covering this topic [2][3].
[1] http://www.iviking.org/?page=FX.php
[2] http://www.moyergroup.com/publish.php?sub=whitepaper
[3] http://www.filemakerprofis.de/modules.php?op=modload&name=tutorial&file=details&func=chapter&nr=1
