Question: A bunch of sites, such as <http://scaleofuniverse.com/>, have zoomable interfaces that will allow you to "zoom through" items to reveal "smaller" items contained within them. I have always seen this done in Flash, but am wondering how it could be made using JavaScript and CSS. Is there any open-source library out there that supports this feature?

Also, I have had a look at impress.js, which has some very cool features, but I am unsure whether I would be able to accomplish the desired effect using this library. Is it just a matter of using the right CSS styles?

Answer: 
The process is very complex but its doable, here is a great article on how to come up about it, [Create a zoomable user interface with CSS3](http://www.netmagazine.com/tutorials/create-zoomable-user-interface), and also a jQuery plugin that provides a close effect that you are looking for, [Zoomooz](http://janne.aukia.com/zoomooz/).
I ended up using a stripped-down version of [zoom.js](http://lab.hakim.se/zoom-js/), which provides the ability to zoom in on any DOM element. It is similar to Zoomooz, but much less bloated and gave me the possibility to isolate the few lines of code that were necessary to achieve the effect without needing to load an external library.