There are a lot of fine Javascript files (libraries/frameworks) - both for plain Javascript and for jquery on the market, both free and commercials, but they all need to be loaded (installed) into Your Confluence to utilize:

 

First, All of the stuff below is quite generic and samples only, refer to the documentation.

Second, all the files are considered "foreign" (including symbolic links) during an upgrade and must be reimplemented.

Some lightboxes:

 

prettyPhoto (Best, and actually free (thumbs up) - does not support slide on iOS ) 

FloatBox (Best, not free for commercial sites)

Flare (Not free)

Slimbox2 (Free, not good on mobile devices)

OrangeBox (Free)

FancyBox

LightView (Free)

See more at http://www.tripwiremagazine.com/2013/06/jquery-lightbox-plugins.html

Install below Confluence

Download the Javascript files/Framework zip, upload it to the server and place the files under the install:

cd /opt/confluence/confluence
mkdir mylightbox
cd mylightbox
mv ~/mylightbox.zip .
unzip mylightbox.zip

Somewhere else in the filesystem with symbolic linking

Along the way, I have given up having individual symbolic links pr. library/framework, so now I place all under "confluence-ext-libs"

Download the Javascript files/Framework zip, upload it to the server and place the files under the install:

This requires support for Linking in Tomcat. the server.xml file has to be changed adding the allowedLinked parameter:

 

<Context path="" docBase="../confluence" debug="0" reloadable="false" useHttpOnly="true" allowLinking="true">

 

Create the filestructure:

cd /data
mkdir confluence-ext-libs
mkdir mylightbox
cd mylightbox
mv ~/mylightbox.zip .

unzip mylightbox.zip

Link under Confluence (only needed once)

ln -s /data/confluence-ext-libs  /opt/confluence/confluence/confluence-ext-libs

 

The Common Part

Now these can be referenced as /opt/confluence/confluence in the server root, so in Custom HTML (header part) add:

<!-- MyLightbox -->
<link rel="stylesheet" href="/confluence-ext-libs/mylightbox/css/mylightbox.css" type="text/css" media="screen" charset="utf-8" />
<script src="/confluence-ext-libs/mylightbox/js/jquery.mylightbox.js" type="text/javascript" charset="utf-8"></script>

 

Some lighboxes requires to be initiated (the Jquery reference $ is AJS.$ for Confluence):

<script type="text/javascript" charset="utf-8">
  AJS.$(document).ready(function(){
    AjS.$("a[rel^='mylightbox']").mylightbox();
  });
</script>