GNU TeXmacs from Wikipedia:
"GNU TeXmacs is a free scientific word processor and typesetting component of the GNU Project. It was inspired by TeX and GNU Emacs, though it shares no code with those programs. TeXmacs does use TeX fonts. It is written and maintained by Joris van der Hoeven. The program produces structured documents with a WYSIWYW (what you see is what you want) user interface. New document styles can be created by the user. The editor provides high-quality typesetting algorithms and TeX fonts for publishing professional looking documents."
- web site: http://www.texmacs.org/tmweb/home/welcome.en.html
- download page (Windows version): http://www.texmacs.org/tmweb/download/windows.en.html
- direct download last stable installer (1.99.2): http://www.texmacs.org/Download/ftp/tmftp/windows/TeXmacs-1.99.2-install...
- downloaded archive: MB 38.6
- license: GPL
- videos: http://www.texmacs.org/tmweb/home/videos.en.html
- screenshot: http://www.texmacs.org/tmweb/home/screenshots.en.html
- Plug-ins page: http://www.texmacs.org/tmweb/home/screenshots.en.html
(Yes, it can take formulas from Mathematica by Wolfram Research)
- Documents can be saved in TeXmacs, Xml or Scheme format and printed as Postscript or Pdf files. Converters exist for TeX/LaTeX and Html/Mathml
- User manual can by printed from inside TeXmacs editor.
- Softpedia: http://www.softpedia.com/get/Science-CAD/TeXmacs.shtml