org.civicoop.postcodenl
CiviCRM extension for Dutch postcode checking
This extension uses a table with all the dutch postcodes to autocomplete the addresses on input.
This extension has also an API for retrieving the postcode by different parameters.
Requirements
In order to use the pro6pp database import functionality you need PHP with the Zip extension enabled. See http://www.php.net/manual/en/book.zip.php