aee is a text editor that is intended to be usable with little or no instruction. It provides both a terminal (curses based) interface and native X-Windows interface (in which case the executable is called xae). Features include pop-up menus, journalling (to recover from system crash or loss of connection), cut-and-paste, multiple buffers (associated with files or not), and much more.
Anjuta is a versatile Integrated Development Environment (IDE) for the GNOME desktop. It features a number of advanced programming facilities that include project management, application wizards, an on-board interactive debugger, an integrated glade UI designer, integrated devhelp API help, an integrated valgrind memory profiler, an integrated gprof performance profiler, a class generator, a powerful source editor, source browsing, and more.
ArgoUML is a pure Java open source UML CASE tool that provides cognitive support for object-oriented design. ArgoUML provides some of the same editing and code generation features of a commercial CASE tool, but it focuses on features that enhance usability and support the cognitive needs of designers. Uses XML file formats: XMI and PGML.
GNU Aspell is a spell checker designed to eventually replace Ispell. It can either be used as a library or as an independent spell checker. Its main feature is that it does a superior job of suggesting possible replacements for a misspelled word than just about any other spell checker out there for the English language. Unlike Ispell, Aspell can also easily check documents in UTF-8 without having to use a special dictionary. Aspell will also do its best to respect the current locale setting. Other advantages over Ispell include support for using multiple dictionaries at once and intelligently handling personal dictionaries when more than one Aspell process is open at once.
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.