A Better Finder Rename is a must have app for me. It lets you rename files using various sets of rules, and the latest version 11 is an even bigger upgrade.
You can now add multiple file filterings to a single change making it so different file types have different renaming on a single rename! Wow! And you can save Actions and Presets! And their is now Preview filtering.
This is a must have upgrade for a must have program. I always find it hard to work on a machine that does not have this program installed!