<!-- displayed equation: -->
<center><eq>
U = \sum\limits_{s_1\in S_1} \sum\limits_{s_2\in S_2}
    \left\{ \begin{matrix} 1 & \hbox{if } s_1 > s_2 \cr
                           0 & \hbox{otherwise}\hfill\end{matrix} \right.
</eq></center>

<!-- inline equation: -->
<p>
Consider the binomial coefficient <eq>\textstyle \left(2\;m \atop m\right)</eq>.
</p>

<!-- running gladtex will render the equations as images and generate HTML to include them -->

http://folk.uio.no/martingu/gladtex/

The preprocessor gladtex allows you to put LaTeX equations into HTML files.  I have found its output neater than that of other such formatters.

Put LaTeX equations into HTML

HTML