This is great extension, but it has a serious code flaw in the plugins/system/yoo_effects.php file. After you activate this plugin, check to see if you're getting an error with your rss feeds. If you, this will likely fix it.

1. open plugins/system/yoo_effects.php

2. Locate this code at the bottom of the file:
$document =& JFactory::getDocument();
if ($javascript) $document->addCustomTag($javascript);
if ($lightbox) $document->addStyleSheet($plugin_base . 'lightbox/shadowbox.css');
}

3. Replace with this code:

// add javascript and css
$format = $_GET['format'];
if ( !$format=='feed' ) {
$document =& JFactory::getDocument();
if ($javascript) $document->addCustomTag($javascript);
if ($lightbox) $document->addStyleSheet($plugin_base . 'lightbox/shadowbox.css');
}
}