LyX is a document processor that encourages an approach to writing based on the structure of your documents (WYSIWYM) and not simply their appearance (WYSIWYG). LyX combines the power and flexibility of TeX/LaTeX with the ease of use of a GUI.
Math is the LibreOffice suite's formula editor, that can be invoked in your text documents, spreadsheets, presentations and drawings, to enable you to insert perfectly-formatted mathematical and scientific formulas.
MathType is a powerful interactive equation editor for Windows and Macintosh that lets you create mathematical notation for word processing, web pages, desktop publishing, presentations, elearning, and for TeX, LaTeX, and MathML documents.
KLatexFormula is an easy-to-use graphical application for generating images (that you can drag and drop, copy and paste or save to disk) from LaTeX equations. It is written in Qt4.
Math, part of the Apache OpenOffice suite, is a tool for creating and editing mathematical equations, similar to Microsoft Equation Editor (included in Microsoft Office). The created equations can then be embedded inside other OpenOffice.
VerbTeX is a free, collaborative LaTeX Editor. It allows you to create and manage LaTeX projects directly on your Android device and generate a PDF by using Verbosus (Online LaTeX and Octave Editor)
MathCast is an equation editor, an application that allows you to input mathematical equations. These equations can be used in written documents, webpages, and even databases. They could be rendered graphically to the screen, to picture files, or to MathML - today’s leading...
LaTeXiT is a small utility that allows you to quickly typeset LaTeX equations, without bothering with file creation, preambles, and so on. The PDF image obtained can then be exported by dragn drop to any application supporting it.
Tex2Img is a free online Latex equation editor that converts Latex equations to high resolution images to embed in documents and presentations. You can also use Tex2Img to learn Latex by trial and error.