Ant Renamer is a free program that makes easier the renaming of lots of files and folders by using specified settings. The interface is clean and intuitive. All you have to do is to add files and then use the "Actions" section.
Replacing character strings by others
Inserting a character string
Deleting several characters
Name creation with mp3's Tag (ID v1.1)
Name creation with file's last modified date and time
Random names creation
Case change (uppercase, lowercase, first letter of each word in uppercase, ...)