Is there something in particular your looking to get from it? is it the looks or functionality?
bubble is great in the sense that it has an operator for base64, so using the html element, throwing in
<embed src="data:application/pdf;base64,YOUR-BASE-64" width="100%" height="100%">
or
<embed src="https://YOUR-PDF-URL.com" width="100%" height="100%">
This, although the default, is handy, Its responsive, has a lot of features for nav and view, but will also print/save and is compatible almost everywhere. the good thing for those who prefer not to get too deep into the code they can use this for base64 data in the form of a PDF or image or simply reference a site.
on the other hand http://html5.snowbound.com/ 