how to determine number of files stored in a web site?

is there a way to determine the number of all stored files in a php-based or .net-based web sites? files could be in any format (word, pdf, ppt, excels, images..etc.) i want the result to be written to a report page or anything similar.

even if there's a 3rd party tool that can do the trick, please don't hesitate to share it.

Thanks.