Gaupol is an editor for text-based subtitle files. It supports multiple subtitle file formats and provides means of creating subtitles, editing text, and timing subtitles to match video. The user interface is designed with attention to batch processing of multiple documents and convenience of translating.
K-Yamo is an MP3 and Ogg Vorbis tagger with ID3v2 support. It can store ID3v1, ID3v2.3, or ID3v2.4 tags. It also stores pictures in the tags. K-Yamo supports multi-file editing. It can guess tags out of filenames, and fetches the missing parts from musicbrainz. It also cleans up your files into a structured filesystem tree which makes use of the tags in the files. Finally, it is a CD ripper with FreeDB support. A MySQL database can optionally be used for tagging.
emv is a tool for mass-renaming files with a text editor. It can perform two pass renaming, link creation, file list splitting, and link target editing. emv logs its actions as shell-script-style mv commands in case you want to undo them. It is quite capable when used with the Vim text editor's visual block changes. emv can also be used non-interactively by providing a Perl expression for renaming files. It's especially useful if you want to see all the files at once and want to think about their names while editing and changing whole groups of files.
sfre (system flight recorder editor) is a script that wraps a text editor or any arbitrary command and implements logging, file locking, and change tracking for the command executed. It is meant for helping system administrators manage a system in tandem without interfering with each other.
Bviplus is a console ncurses based binary file editor (hex editor) with Vim-like keys and features. It can quickly open/edit/save very large files (> 2GiB). It can perform regexp-like pattern searches in hex or ASCII windows. It features search highlighting, multiple undo/redo, a tabbed multiple file interface, visual selection, cut and paste (which works between files as well), blob coloring, and more. It can run external programs on selected data, supporting any program that reads stdin and writes stdout. It has few dependencies for easy portability.
Virtaal is a tool for computer-aided translation that offers a simple, user friendly interface. It includes powerful features such as translation memory, terminology management, and placeable handling. Virtaal can edit files such as Gettext PO, XLIFF, and various other localization formats.