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.
Scilab is a numerical computation system similiar to Matlab or Simulink. Scilab includes hundreds of mathematical functions, and programs from various languages (such as C or Fortran) can be added interactively. It has sophisticated data structures (including lists, polynomials, rational functions, and linear systems), an interpreter, and a high-level programming language. Scilab has been designed to be an open system where the user can define new data types and operations on these data types by using overloading. A number of toolboxes are available with the system.
jHepWork (jWork) is an environment for scientific computation, data analysis, and data visualization for scientists, engineers, and students. The program is fully multi-platform (written in Java). Programs can be written in the Java, Jython/Python, and BeanShell scripting languages. Matlab/Octave is supported for symbolic calculations. The program can be used to display data and functions in D and 3D. It comes with a friendly IDE and a code assist.
EFEU is suitable for handling data cubes, which are especially useful for building data warehouses. It consists of a building system including mkmf (a xmkmf like Makefile generator), esh (a powerful C/C++ interpreter), efeudoc (a document generator with different output formats (LaTeX, HTML, roff, etc.)). EFEU has a huge set of C library core features, including robust memory allocation tools, functions to concatenate and copy strings with memory allocation, buffers for dynamically-growing strings and fields, data structures with reference counters and garbage collection, and file tools that allow you to specify pipes wherever a filename is expected and support automatic implementation of (de)compression filters (gzip) depending on filename extensions. It also includes a high-level interface to files, strings, and anything else you can read from or write to.
iloog is a Gentoo-based live CD targeted mainly at students and scientists. It features UnionFS filesystem support that enables you to write everywhere on the LiveCD and install extra packages, a graphical X environment through the Fluxbox window manager, many programming editors and IDEs, and a plethora of scientific applications, including Octave, Namd, Merlin, and full (La)TeX support.