BookAnd is an Android app which lets you build and share a virtual ebookstore. Well, they call it a bookstore but since you cannot actually sell stuff I see it as more of a virtual private library.
You can choose from 4 different themes to build your library. In addition to the books, you can also stock the library with various 3D furniture and accessories to suit your disposition. The app will help you pull in book covers, metatdata, and reviews from other websites, making it easy to fill the shelves with books you like.
The organizational possibilities here are perhaps the most interesting.You can place the virtual books on the shelf in whichever order you like, and that means the order can sometimes give away details about how people think. It's always fun to see the connections others make between books; chances are I might learn something.
And once you're done building the library you can share it with other users. I don't see any way to comment on each other's libraries, but you can browse them and secretly judge the owner based on which books they own.
Of course, the idea isn't that new. Any nosy bookworm has the habit of scanning a bookshelf to see what the owner likes to read, and this is likely where the developers got the idea. Even among the digiterati, snobbishly judging someone by their bookshelf is old hat. Goodreads, for example, lets you assemble a list of books and then share it. (The judging happens kinda automatically.)
Aside from the visual browsing aspect (which is rather cool), I think the Goodreads method might be better. Lists with links to discrete pages strikes me as the better approach. I'm rarely a fan of 3D, and my rule is to avoid it where possible.