aNobii, AJAX & the User Experience

I’m really becoming addicted to aNobii, and I like for a couple of reasons.
I like it as a social tool, because among DVD, CD and Books, the last are better hit (or, they can benefit more) from the “[tag]social network[/tag] effect”, i.e. from the exchange of user reviews, comments and whatever, so it’s easy to discover “users with similar bookshelfs”.
But I really like it also because it has one of the best user interfaces I’ve ever seen in a web application.
The result of an intelligent use of javascript ([tag]AJAX[/tag], actually) is a very clean and “reactive” interface, which is, at the same time, limited to the essential (and useful) elements.
Just to give you an example, I’m posting a picture of the ISBN validation textbox. Very nice.

[tags]web2.0, aNobii[/tags]