I just released a little utility I wrote called CopyUnique that will copy all the files in a directory tree using sequentially numbered filenames. Ok, but why would someone want to do this? Well, I primarily use it to number all the ripped audio tracks from a set of audio book CDs. CopyUnique fixes up the filenames so they can be burned to an MP3 CD and played sequentially on my car's MP3 player. CopyUnique could also be used to copy several directories worth of digital pictures into a sequentially numbered slideshow directory. A better description as well as a link to the download is on my web site's CopyUnique project page.