LyX

LyX is the first WYSIWYM document processor that encourages an approach to writing based on the structure of your documents, not their appearance. It is released under a Free Software / Open Source license.

LyX is for people that write and want their writing to look great, right out of the box. No more endless tinkering with formatting details, 'finger painting' font attributes or futzing around with page boundaries. You just write. In the background, Prof. Knuth's legendary TeX typesetting engine makes you look good.