Added Shadowbox

Shadowbox is a web-based media viewer application that supports all of
the web's most popular media publishing formats. Shadowbox is written
entirely in JavaScript and CSS and is highly customizable. Using
Shadowbox, website authors can showcase a wide assortment of media in
all major browsers without navigating users away from the linking page.

Just add : rel="shadowbox"
to <a href="/just/a/link">just a link</a>
like this : <a href="/just/a/link" rel="shadowbox">just a link</a>

For more information : http://www.shadowbox-js.com/