A9: The next big thing?

Search engine tracker John Battelle thinks Amazon's A9 search engine, fresh out of beta testing this week, is the Web's next great app. Built by ex-Yahoo guru Udi Manber, what makes A9 different from the others is that it takes what makes Yahoo (depth of searches) and Google (more meaningful results) great and adds another layer on top: personalization.

A9 not only provides search results like every other engine, but uses two new presentation methods to enhance the experience. First, you can view different types of search results from one query in different panes on the same screen, so you'll search images, the Web, IMDb and Amazon's millions of searchable book pages all at once.

Second, and perhaps more importantly, A9 takes Amazon's heralded recommendation system (Visitors who bought "Charlie and the Chocolate Factory" also considered...) and melds it into search results, so that as it keeps track of what you're doing, providing feedback and reminding you about which results you used in past queries, it also watches everyone else's clicks and gives you feedback about what other people did with the results.

The success of this "Discover" feature (your results are called "Recover") depend a great deal on how many people adopt A9 as their search engine of preference, of course, but over time it may be the one thing that separates the search winners from the also-rans.