Rename Master (free)

Rename Master is a utility for renaming large groups of files with a few clicks. Anyone that has worked with websites, file archives, or collections of music, videos, or pictures has probably spent way too much time renaming hundreds of files. The program provides an easy to use interface that allows you to perform simple and advanced rename operations, very easily. You can even preview the to-be-renamed file names before you finalize it and apply any changes. Advanced renaming features include adding, removing from the original file name, replacing characters (name or extension) and support for several meta variables, that allow you to perform renaming based on the files size, date and several other criteria. Renaming operations can be saved as scripts, so they can easily be reused at a later time. Additional features include optional Explorer integration, uppercase/lowercase conversion, file filters and more. A powerful, yet easy to use renaming utility!
http://www.snapfiles.com/get/renamemaster.html