Beaver is an Early AdVanced EditoR, for Linux and other Unices (and even Windows); in other words, it's a text editor that is intended to be light-weight, but full of useful features for programming, from editing of web sites to C coding. It is based upon the GTK+ toolkit, supports many languages, and offers functions such as automatic indentation and syntax highlighting.
Bibcursed is a simple curses-based editor for BibTeX bibliography files, especially useful for those who have to maintain a large number of references for a major piece of documentation, like a PhD thesis. It performs everyday functions such as adding, removing and viewing reference entries. Intelligent prompting for fields is used when adding entries so that authors do not have to rely on memory for knowing which fields can and cannot be used for different entry types.
Bluefish is a programmer's Web development editor written using GTK, designed to save the experienced webmaster some keystrokes. It features a multiple file editor, multiple toolbars, custom menus, image and thumbnail dialogs, open from the Web, CSS dialogs, PHP, HTML, Java, C, and XML support, external program integration (tidy, weblint, make, javac), and lots of wizards.
Boxes is a text filter that can draw any kind of box around its input text. Box design choices range from simple boxes to complex ASCII art. A box can also be removed and repaired, even if it has been badly damaged by editing of the text inside. Since the generated boxes may be open on any side, the program can also be used to create regional comments in any programming language. New box designs of all sorts can easily be added and shared by appending to a free format configuration file. In addition to being a command line tool, Boxes integrates well with any text editor that supports filters.
Cooledit is a text editor for the X Window System. It contains a built-in Python interpreter for macro programming, and it includes a rich set of utilities and features. It has multiple edit windows and a beautiful, intuitive user interface that requires no tutoring to learn to use. It can be used as a programmer's IDE and has syntax highlighting for a large number of programming languages. It contains an interactive graphical debugger for C/C++ programs.
e93 is a portable window-based text editor oriented to the needs of programmers. It uses the mouse, selections, cut/copy/paste, and closely follows the model of editors on the Macintosh and NeXT platforms. It supports columnar selection by allowing multiple pieces of the text to be selected simultaneously (this is perhaps its most unique feature), imposes no limits on the line length, file length, or number of simultaneous files which it can edit, and has many other features.
Elvis is a clone of vi/ex, the standard UNIX editor. Elvis supports nearly all of the vi/ex commands, in both visual mode and ex mode. Elvis adds support for multiple files, multiple windows, a variety of display modes including "hex" and "html", on-line help, WYSIWYG printing, and other miscellaneous extensions.