[MassFileRenamer] - This tool was created to rename huge collections of files, usually of the same file type. Good file operations source code reference and user guide.
[AutoRename] - Automatically rename files in a directory (with subdirectories if wanted) according a certain mask. A log file can be written optionally.
[MasiveFileRenamer] - C# source code that demostrate how to massively rename files listing from an specified folder. complete source code,has passed the test.