Métamorphose (Version: 2 (0.8.2 beta) as of this post. That is a beta of version 2) is a powerful, some may say somewhat complicated, renamer program. It works well whether working with few or thousands of files.
The first step is to pick the files and/or folders to be renamed using the Picker tab. Here filters on file types (dropdown immediately below the browse dropdown), case sensitivity and unicode file names (right of the aforementioned file type drowdown) can be picked. Also the recursive option checked to work on subfolders to any number of depths.
The Renamer tab can support any number of operations. Available renaming operations include putting the directory path into the file name, inserting text in any position in the files, replacing text, swapping text, modifying text (to upper case, removing certain characters, etc.) and more. Each time the operation can occur based on regular expressions, for example if a file name includes upper case it can be ignored.
All operations can be sorted to occur in different sequences and also ‘destroyed’ to be deleted. There are options for incremental numbering and date based renaming as well (see image below). A preview is immediately shown when at least one operation is chosen.
The Sorting panel or tab lets files be sorted manually or automatically, this basically lets the user choose to do the renaming operations in different order, for example in descending or ascending file name.
The Help menu has examples, a help file and a page on regular expressions that may be used with the program. Métamorphose is cross platform, works on Windows 2000 and newer and is available via Ubuntu’s Update Manager among other places.