Name Mangler

namemangler_small.png If you’re looking for a batch renamer for MacOSX, Name Mangler is definitely worth your while.
You can set your extension, rename with sequential numbers, use regular expressions, and do a whole bunch of other types of things to the files themselves. There are even more advanced features like drag-n-drop task based renaming, nested counters, and a whole lot more. Donationware for MacOSX.