So Amazon is getting into the search business, eh? Yesterday the online retail monster unveiled A9, which appears to be a promising new addition to the search engine world. First of all, it relies on Google’s search results, so you can’t go wrong there. But it also adds several intriguing features of its own.

Signing into your Amazon account (if you have one) helps A9 to customize your search experience (I know, those of you with privacy concerns are cringing now….). The main search page is very simple, a la Google. The search results page is tabbed; the first tab will show you Amazon search results for your query, if any exist — it will also include the “Search Inside The Book” results. The second tab keeps track of your search history, so you have easy access to searches you have run before.

You can also perform an A9 query from anywhere on the Internet, from your address bar — just type a9.com/query, and you’ll be taken to your results. (I’m still playing with this — I’m not sure how you enter a multi-term query in a URL format).

As with all search engines, there’s the ubiquitous toolbar. In addition to the usual features, it contains a diary feature that allows you to make notes on any website you visit, and then reference those notes any time you re-visit that site from any computer.

Of course, with all these good features, you’d have to expect that A9 would want more of your personal information. And you’d be right. As I said before, A9 keeps track of your search history — and it also keeps track of your “click history” — if your search results include a site you have seen before, A9 will let you know, and even tell you the date you last visited the site.

For reviews of A9 and what it means to Google, click here and here.