Vimlatex?

http://vim-latex.sourceforge.net/

LaTeX is probably what you want for such a project. There is a certain learning curve, but once you get past that, you've mastered a text processing framework that's quite flexible, and basically the industry standard in many fields (e.g. mathematics and physics). It can be used with any editor, but I second mfillpot's suggestion of Texmaker if this is your first time trying LaTeX, since it features a graphical user interface for generating preambles, including graphics and tables, inserting symbols etc. That makes the learning curve more gentle.

Once you've mastered LaTeX somewhat, any editor will do; I personally prefer Vim, but I have to admit that the preview-latex package for Emacs is quite awesome. If you want something semi-wysiwig, Gummi is also a bit interesting.

Depending on your needs, you might also want to consider something like LyX or txt2tags. Both of them has the ability to generate TeX output for you, which can be compiled into the same professional-looking output that using LaTeX directly would offer.