This code will display all subfolders and files of whatever directory it's in. It uses the readdir() PHP function to get the directory contents, and displays each item as a link. If you want this script to work recursively to display the contents of subfolders, just save it as 'index.php' in each folder and subfolder.
$myDirectory = opendir(".");
while($thisfile = readdir($myDirectory))
{
$dirArray[] = $thisfile;
}
closedir($myDirectory);
sort($dirArray);
for($i=0; $index< count($dirArray); $i++)
{
echo("<a href=\"$dirArray[$i]\">$dirArray[$i]</a>");
//echo(" - " . filetype($dirArray[$index])); //optional
//echo(" - " . filesize($dirArray[$index])); //optional
echo("<br />\n");
}