Create a WYSIWYG Online Equation editor using Javascript and HTML5

We need equation editor that looks like the typical equation editor that you would find in Word, or MathType, but that can be used on a website, without reliance on flash. The output of the editor would be the LaTeX code corresponding to the user input. Existing equation editors without flash, such as the one implemented on CodeCogs, become complicated to use for those not versed in LaTeX, and are not directly WYSIWYG. We want a user to be able to click an icon for fractions, and then see an empty numerator field over a denominator field, for example. It's also critical that we have the ability to add in our own skins after the fact. For example, we may want to use different icons for the different parts of the equation editor, or may want to limit which parts of the equation editor are shown by default.