You can easily create a popup using a regular div element and some CSS. In particular, the position: fixed CSS property allows you to put something in a position in a window, no matter how it scrolls.
Here is a simple JSFiddle demonstrating the technique: http://jsfiddle.net/BinaryMuse/ndr2Q/

You can click on the titles of the books to expand their description, which I hope will make the preview window tall enough to scroll. (If not, just resize the window.) No matter where in the scrollable document the pop-up window (which is a regular element with ng-show and some CSS) is in the lower right corner of the screen.
You can find libraries such as Bootstrap, which are jQuery plugins so you can create pop-ups on a page, but in general they are designed to prevent user interaction with page after modal in any useful way. This method allows you to scroll and use the page in the background, similar to the Gmail interface.
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