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.
GNU TeXmacs is a free wysiwyw (what you see is what you want) editing platform with special features for scientists. The software aims to provide a unified and user friendly framework for editing structured documents with different types of content: text, mathematics, graphics, interactive content. TeXmacs can also be used as an interface to many external systems for computer algebra, numerical analysis, and statistics. New presentation styles can be written by the user and new features can be added to the editor using Scheme.
KOffice is an integrated office suite based on the KDE libraries. KOffice currently includes KWord, KSpread, KPresenter, KChart, Karbon14, Krita, Kexi, KFormula, Kugar, and Kivio. There are no special mail and news clients included in KOffice, because there are KMail and KNode available for KDE anyway. All KOffice components work together, and you can embed every KOffice component into any other KOffice component. This is realized using the KParts object model.
LyX is a document processor that encourages an approach to writing based on the structure of your documents, not their appearance. It is intended for people people who write and want their writing to look great without tinkering with formatting details, font attributes, or page boundaries. On screen, it looks like any word processor, but it uses the TeX engine for printed output and producing richly cross-referenced PDFs. It is stable and fully featured.
Siag Office is a free office package which consists of the spreadsheet Siag, the word processor PW, the animation program Egon, the text editor XedPlus, the file manager Xfiler and the previewer Gvu. Siag is easy to use, yet infinitely flexible through multiple embedded interpreters and a plugin mechanism that allows other programs to run inside the main document. The supported interpreters are SIOD, Guile, Tcl, and Python.
gtex-letter attempts to deliver an easy alternative interface to LaTeX-letter. It is heavily configurable, and it supports multiple letter headers and default letter openings (which are configurable in the rc-file). Users can choose from three different levels of graphical interface complexity. Novice is easy to understand, while expert is straight-forward. There is also a non-interactive mode that makes production of standard-letters very fast. gtex-letter is implemented in Python and based on GNOME.