TeXmacs

TeXmacs provides a unified and user-friendly framework for editing structured documents with different types of content: text, mathematics, graphics, interactive content, slides, etc.
TeXmacs can be used as a graphical front-end for many systems in computer algebra, numerical analysis, statistics, etc.
Documents can be saved in TeXmacs, XML, or Scheme format and printed as Pdf or Postscript files. Converters exist for TeX/LaTeX and Html/MathML.
Its rendering engine uses high-quality typesetting algorithms so as to produce professionally looking documents, which can either be printed out or presented from a laptop.
New styles can be written by the user and new features can be added to the editor using the Scheme extension language.