LyX/Mac - UNIX & Open Source
LyX/MacA is fully-featured implementation of LyX, a WYSIWYM (what-you-see-is-what-you-mean) editor/formatter using the LaTeX formatting engine, on the mac os X native graphics display, with the familiar Aqua GUI look & feel and anti-aliased text. It is particularly well-adapted to complex technical writing, mathematics, and scientific editing and writing, but equally useful for non-scientific writing from a simple letter to articles or books.
Information on installing the teTeX prerequisite, and installing and using LyX/Mac, is available in the howto at http://wiki.lyx.org/pmwiki.php/LyX/Mac.