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.
DictEm is an extremely customizable DICT client for (X)Emacs. It implements all functions of the client part of the DICT protocol (RFC-2229). Unlike dictionary.el, it widely uses autocompletion that is used for selecting a dictionary and search strategy. It provides several hooks that may be used for buffer postprocessing. Built-in hyperlinking and a highlighting mechanism are based on this ability. It supports the mechanism of virtual dictionaries that can be used for grouping dictionaries from different DICT servers into the client-side virtual dictionary.