I got shadowbox to work for me in Magento, very similar to lightbox. This is how I did so. Simply add shadowbox to Magento by adding the core js and css files.
This answer assumes you have jQuery installed and running properly, check this link for shadowbox's jQuery requirements: https://github.com/mjijackson/shadowbox
to use internally hosted files, download latest version and place the following code in: /app/design/frontend/default/[YourTheme]/layout/local.xml
<default>
<reference name="head">
<action method="addItem"><type>skin_css</type><name>js/shadowbox.css</name></action>
<action method="addItem"><type>skin_js</type><name>js/shadowbox.js</name></action>
</reference>
</default>
place shadowbox.css and shadowbox.js in your /skin/frontend/default/[YourTheme]/js/ folder. Then you can add the attribute rel="shadowbox" to your links to open with shadowbox, such as:
<a href="http://saneldesign.com/..srcu-jadrana.html" rel="shadowbox">
<i class="icon-eye-open icon-white"></i>
Pregled </a>
If you wish to run shadowbox sitewide, you must initialize by adding the following code in the Admin > System > Configuration > General > Design > Footer > Miscellaneous HTML:
<script type="text/javascript">
Shadowbox.init();
</script>
If you get any javascript errors you may need to check for conflicts ($), prototype and make sure jQuery, especially shadowbox is running in no conflict mode. I use the following code and change $ to $j as needed within jQuery files.
var $j = jQuery.noConflict();
There are additional configuration options here: http://shadowbox-js.com/options.html