New search engine from Amazon.com, includes a personal search history that can be accessed from any computer and if you have the IE toolbar installed, access to Amazon's information about the page you are viewing with a diary feature that allows you to annotate any page you visit.

Search results are provided by Google and users can also use Amazon's search inside the book feature.

For more information, read a full review by battellemedia.com, or discussion on metafilter.com

Update: Download an a9 search plugin for Mozilla Firefox