AListApart's styleswitching Javascript is good if you only have two stylesheets to switch between.  But what if you want multiple sheets?  For example, I want the user to be able to use any font-size from 7px to 24px when reading my main page.  For this, I modified the original <code>styleswitcher.js</code> to fit my need.  The only requirements are that all of the sheets be linked in the document header, that the default sheet be placed first and that all of the sheets to switch between have a "title" attribute (to distinguish them from the always-active sheets).  I haven't put it up yet, because it makes ugly html and I haven't figured out how to make it work with my font-switcher div.

In the meantime, I'll be working on a better solution.