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.
GtkMathView is a GTK widget for rendering MathML documents. It is meant to be a standalone, light-weight component and not a full browser. GTK applications can use the widget as a window for displaying mathematical formulas and doing simple interactions. Among other features, GtkMathView includes support for breaking long mathematical expressions, rendering of stretchy operators, and provides a customizable support for additional fonts.
ASCIIMathML is a script that converts calculator-style ASCII math notation (and many LaTeX formulas) to Presentation MathML while your Web page loads. It works with HTML and XHTML files in Mozilla/Firefox/Netscape 7+ browsers, as well as in Internet Explorer 6 with MathPlayer. For example, the solutions for the equation 'ax^2+bx+c=0' are expressed in the HTML file as '(-b +- sqrt(b^2 - 4ac))/(2a)', and display as nicely formatted MathML. The script can be easily used in wikiservers and blogs, as a rudimentary MathML editor (with instant preview), and to preview math formulas as they are typed into a Web page input area.