1. Other options
Note: Style switcher

2. Navigation/Menus
You've seen the version I added from webbedenvironments. Other sources (OpenCube) are probably more promising
Note the event handlers, how visibility is changed, use of position:relative, contextual links (a.menulink:hover)..
Other options such as slide-in, tabbed (try Spry accordion widget)

3. Content
Several ways to add, update content on the fly using AJAX (Asynchronous JavaScript And XML) apps. These depend on
document.getElementById(objectID).innerHTML=pageRequest.newText
Also can control form options based on what user inputs, or create dynamic type ahead text in forms
Same principles use AJAX to get text for dynamic popup messages (if not working see demo on webbedenvironments site)

4. Style Controls
This chapter has another option for changing the style of a whole page. This is actually a fairly simple script (no AJAX) that uses ids in the style tags to import a new sheet
<style id="style1" tpe="text/css">
@import url(style1.css);
</style>