Shadowbox is a cross-browser, cross-platform, cleanly-coded and fully-documented media viewer application written entirely in JavaScript. Using Shadowbox, website authors can display a wide assortment of media in all major browsers without navigating away from the linking page.

Download:

NinjaForge

Demo:

Ninja Demos Shadowbox

You can show images, flash files, webpages, hidden inline content. 

Example for hidden Inline Content

You will need to add the width and height options to the rel attribute. The link refers to content in a 'div' within this page with a style of 'display: none'.

The code:

<a rel="shadowbox;width=500;height=200" title="" href="/index.html#inline-sample">Hidden Inline Content</a>
<div id="inline-sample" style="display: none;">
<p>This content was taken from a hidden div somewhere in this page!</p>
<ul><li>Dill = Bloody stupid</li><li>build = See above :-(</li><li>Geek = Pretty bloody smart</li><li>Wizzud = See above :-)</li></ul>
</div>

This example is take from Shadowbox.js Sandpit. There are other useful examples.

Show several images in one gallery:

rel="shadowbox[galery1];height=1000;width=500;"

Show the content from one gallery in slideshow. Add options={slideshowDelay:5};. Example:

rel="shadowbox[galery1];options={slideshowDelay:5};height=1000;width=500;"