How To List Files In A Directory + Subdirectory And Then Use Them.

$directory = "./"
function listfiles($directory) {
//here should go the script to list the files in those directories. so that i can continue to work with them. like for example if there were images it would list all  the images and i could write a script to make a thumb of them and then save it into a thumb folder(not asking for all of that). but how would i make it list it.

// basicly what i need is a loop for the files and a echo that lists them.
}

I would like to present these two simple functions for generating a complete directory listing - as I feel the other examples are to restrictive in terms of usage.

function dirTree($dir) {
   $d = dir($dir);
   while (false !== ($entry = $d->read())) {
       if($entry != '.' && $entry != '..' && is_dir($dir.$entry))
           $arDir[$entry] = dirTree($dir.$entry.'/');
   }
   $d->close();
   return $arDir;
}

function printTree($array, $level=0) {
   foreach($array as $key => $value) {
       echo "<div class='dir' style='width: ".($level*20)."px;'> </div>".$key."<br/>\n";
       if(is_array($value))
           printTree($value, $level+1);
   }
}

Usage is as simple as this:
$dir = "<any directory you like>";
$arDirTree = dirTree($dir);
printTree($arDirTree);

It is easy to add files to the tree also - so enjoy.