LyX

LyX is an open source, graphical user interface document processor based on the LaTeX typesetting system. Unlike most word processors, which follow the WYSIWYG ("what you see is what you get") paradigm, LyX has a WYSIWYM ("what you see is what you mean") approach, where what shows up on the screen roughly depicts the semantic structure of the page and is only an approximation of the document produced by TeX.