Extending form validation functions
function where_ever_extra_data_originates_from() {
  $extra_data_to_pass_on_stored_here = &amp;drupal_static(__FUNCTION__);
  $extra_data_to_pass_on_stored_here = $actual_extra_data
}

function my_validation_function($form, &amp;$form_state) {
  //Here's our extra stuff now
  $extra_data = &amp;drupal_static(where_ever_extra_data_originates_from);
}