case-insensitive array_unique

function array_iunique( $array ) {
    return array_intersect_key(
        $array,
        array_unique( array_map( "strtolower", $array ) )
    );
}

You're setting both lvalue and uvalue to the lower case version.

 $uvalue = strtolower($value);

should be

 $uvalue = strtoupper($value);

That said, this might be a little faster. The performance of your function will degrade exponentially, while this will be more or less linear (at a guess, not a comp-sci major...)

<?php

function array_iunique($ar) {
  $uniq = array();
  foreach ($ar as $value)
    $uniq[strtolower($value)] = $value;
  return array_values($uniq);
}
?>