I recently completed a website that catalogs books and in the development I wanted to make something really new. The backend is all ASP.NET, implementing UrlRewriter.NET and AJAX.NET libraries. The frontend uses several JavaScript libraries including Prototype, Scriptaculous, and Tablesort.
The one really unique feature of the site is the 3D bookshelf built using Papervision3D. Just yesterday it was featured in blog Daily PV3D as Papervision showcase.
You can check out the book shelf here:
http://www.bestcommentaries.com/category/proverbs/
Screenshots
Plain bookshelf:
Mouse over the third book from the left:
Book clicked:
How it works
Using Papervision, it's relatively easy to make a 6 sided polygon (cube) and then wrap images around it. I use the physical dimensions of the actual book to size the cube. Then, for the cover, I use an image of the book and wrap the last pixel around the side since I don't have spin images. I tried using System.Drawing code to write the author's name on the spine, but I could never get it to look just right, so I left it out. The only real catch was that I needed to place the shelf on a different Papervision scene to prevent clipping problems. The bookshelf also interacts with an HTML table down below via Flash's JavaScript ExternalInterface.
Since developing this 3D bookshelf, I found one site that does something somewhat similar, but they have the spine images which I can't afford to find for 1000s of books. Also, I think that the JavaScript interaction on mine might give it an edge.