class.upload.php is a powerful and mature PHP class to manage uploaded files, and manipulate images in many ways. The script is available under a GPL license.
more info about the class
$newmenu->no_script = false; $newmenu->allowed[] = 'text/html';
$newmenu->no_script = false; $newmenu->allowed = array('text/html');
Or, if you want to only allow HTML files: