The Wall Street Journal today reported on how Amazon has begun testing its new search engine, named A9.

"Where A9 seems to take a more distinctive approach to searching is with a feature that displays a users' history of searches on the site so that they can quickly resume prior hunts for information."

Just a new face to all the other personalized search services with Book Results as well. So when you do a search on Web design you can click on open book results and A9 will find matches within books. In addition, A9 will show "your search history, which keeps track of which searches you have done in the past, and what search results you have seen and clicked on."