From JellyandCustard.com today, there's a good example of creating and using a DirectoryIterator instance to loop through the files in a directory.
During the days of PHP4, the most common way of showing the files in a directory was like so [opendir, readdir, closedir]. However, if your PHP version has now been upgraded to PHP 5, you can take advantage of DirectoryIterator instead. This class (don't get scared) is part of the SPL library that is now bundled within PHP 5.
They describe the functionality and provide a simple example of its use. Also included are the other functions you can use with the resulting file handles to make for a cleaner interface in your script. They also include two examples of its usage with the output it would give - getting some stats on selected files.