With a slight extension of the wiki syntax with can use the excellent service provided here:
http://www.codecogs.com/components/equationeditor/equationeditor.php to generate nice layouted formulas on the fly.
I suggust to add a new syntax which would convert something like...
[latex]\frac{1}{2} - \frac{1}{2}\cos(x)[/latex]
into this html code:
<a href="http://www.codecogs.com">
<img src="http://www.codecogs.com/gif.latex?\frac{1}{2}&space;-&space;\frac{1}{2}\cos(x)"
alt="\frac{1}{2} - \frac{1}{2}\cos(x)"/>
</a>
Which would then show up as a nicely layouted image.