Peter Maurer’s File List… makes renaming large numbers of files (like, oh, DPX sequences for instance) a snap.

Drag in some files or folders into the main window and set the type of operation to perform. There are a lot of presets available, like renaming extensions, renumbering, or doing search-and-replace type stuff. Those of you who are so inclined can use scripting to do more advanced stuff…

I’ve been just using OSX’s Automator for this type of thing until now, but this is much faster and more intuitive.

It’s free to use, and donate if you like it.