For a surprisingly long time, communicating rich mathematical formulas has been difficult on the Web, in e-mail, or in plain text discussion groups. There are two tools that take the pain out of this process.
Codecogs offers a very nice equation editor, with a complete set of WYSIWYG buttons that operate a workspace which builds an equation in LaTeX, while rendering a graphic image in real-time. The resulting image can be exported in various graphic formats, or the LaTeX can be copied to your clipboard.
Avital Oliver wrote a lightweight browser plug-in for Firefox which renders LaTeX equations, called TEX THE WORLD. It has since been ported to Google Chrome. It scans every web page for equations between [; and ;] and renders them automatically.
Together these make it possible to easily produce LaTeX formulas, already legible to scientific professionals and able to survive the plainest of ASCII environments, and to view them as rich formulas if rendered through a modern web browser.