Try TF3D Config. It will let you change between themes and back to stock without fear of messing anything up. Here's a link to the thread over on XDA-Developers discussing it:
http://forum.xda-developers.com/showthread.php?t=405749
Then look in here. About 2/3 of the way down the post, is a section on themes. It includes TF3D Config as well as a ton of other great files for your TP. It's a collection you download from rapidshare that has most everything you could want for the TP, including theme files. You can search for the individual titles if you're not familiar with the programs and what they do:
http://forum.ppcgeeks.com/showpost.p...&postcount=468
A lot of the files can be downloaded individually and there are links to the threads discussing most in the Touch Pro Essentials thread:
http://forum.ppcgeeks.com/showthread.php?t=42730