MathBook: An XML Application
XSL transform to LaTeX http://buzzard.ups.edu/mathbook/article-latex.xsl
XSL transform to XHTML http://buzzard.ups.edu/mathbook/article-html.xsl
Example XML document http://buzzard.ups.edu/mathbook/calculus-article.xml
To use, for example, put all files in the same directory and issue
xsltproc article-latex.xsl calculus-article.xml > calculus-article.tex pdflatex calculus-article.tex
Or you should be able to preview