Freename
When you use Freename to rename a bunch of files, it will send a text file with all filenames to your text editor. At that point, you can use all available tools of your text editor to change the filenames into whatever you want them to be. You can edit them by hand, you can do a search-and-replace for substrings, and with the right text editors you can use regular expressions, block modifications and lots of things more. You then close your editor, and Freename will carry change the filenames exactly into what you wrote.
