Another way to do it is by using a public LaTeX server, using standard LaTeX code. An example of a public LaTeX server is http://l.wordpress.com/latex.php?latex=. As an example, http://l.wordpress.com/latex.php?latex=int_{-infty }^{infty }e^{-x^{2}};dx=sqrt{pi }&bg=fff&s=2.
One way to use it is by using the img tag of HTML.
For example,
<img src="http://l.wordpress.com/latex.php?latex=
int_{-infty}^{infty}e^{-x^{2}};dx=sqrt{pi }&bg=fff&s=2" alt="" />
will produce this image.
However, it is a messy and error prone job to do it this way.
Fortunately, there is an alternative, for Wordpress user. A PhD student at Center for Advanced Study and Institute for Theoretical Computer Science, Tsinghua University, Zhiqiang Zhang had created a plugin for Wordpress, called Latex for Wordpress. This plugin uses LaTeX code to generate images. Although the plugin uses the Wordpress public LaTeX server, a local LaTeX service such as MimeTex is preferable, in case the public server is down. Some Web hosting support MimeTeX by default.
With this plugin, adding Maths notation is as easy as adding the LaTeX code. For example, for displaying an inline math equation, use
$$int_{-infty }^{infty }e^{-x^{2}};dx=sqrt{pi }!$$
and, for the math mode, use$$!int_{-infty }^{infty }e^{-x^{2}};dx=sqrt{pi }!$$
Notice that there is an exclamation mark "!", just after the second dollar sign.Download Link: http://wordpress.org/extend/plugins/latex/
Update: You can also try the new Easy LaTeX plugin by Manoj.
Note: If you have trouble in writing the LaTeX code, use TeXaide.