$skills = array('WAMP' =>
        array(
            'HTML'
            ,'CSS'
            ,'JavaScript' => array(
                'jQuery','JSON','AJAX'
            )
            ,'XML'
            ,'PHP' => array(
                'OOP'
            ),
            'SQL' => array(
                'MySQL'
            )
        )
    );

$key = 'WordPress vb.';

if(in_array($key,$skills) !== false){
    printf('%s','pm');
}else{
    die('ich bin nicht.');
}