Inquisitor is a bit different, however, whereas the other two will provide suggestions for actual searches, Inquisitor will bring up specific websites as suggestions. A post on the Yahoo Search Blog says:

Building on the work by the Yahoo! Research team in the paper "Information Re-Retrieval: Repeat Queries in Yahoo! Logs," the algorithm that generates the personalized results has been enhanced to return more targeted results.

We’ve also included a bookmark-based retrieval feature for IE. So, if you are looking for a page you bookmarked a few months ago, say an expense report guide on your local Intranet, you won’t need to fumble around your hundreds of bookmarks and folders to find that page. A simple search in Inquisitor will bring it right up.

Is this going to be the revolutionary search feature Yahoo is looking for in its ongoing struggle to compete with Google? Probably not, but it’s a handy enough feature that some users will find useful. Clearly Safari users have already enjoyed it.

It’s faster to type 3 or 4 characters than a dozen or more, something that made Yahoo’s Search Assist an appealing addition to the company’s search service. Start typing and the service suggests possible queries based on what has been typed.

Bringing that functionality into the Safari browser directly came from Yahoo’s acquisition of Inquisitor, a Safari plug-in. Inquisitor offered an auto-complete technology on the Mac side that Yahoo could use.

The latest update to it, according to the Yahoo Search blog, makes Inquisitor a prettier and faster plug-in, with a global reach:

To start with we tapped into the Yahoo! Search infrastructure, using the recently announced Yahoo! Search BOSS, our open search web services platform, in order to speed up the search results delivered in Inquisitor. You should notice a significant improvement in the speed of your query results in Yahoo! Search. We also gave Inquisitor a little facelift with a new, refined, yet simple home page (inquisitorx.com) and a cleaner user interface of the Inquisitor client.

“Independent of these core changes is a slicked up visual design that

 Inquisitor

David Watanabe created the Search Assist-like technology.  He won’t be joining Yahoo, so this isn’t some sort of personnel grab.  Also, even though Inquisitor will use Yahoo as the default search engine, users will be able to switch to Google, Live Search, or whatever else they like, so market shares won’t necessarily be affected.

As for ad revenue, Inquisitor, which is free, is bringing in exactly none at the moment.  Inquisitor was relying on affiliate ad links, and those have been removed.

On the Yahoo Search Blog, Ariel Seidman, Yahoo’s director of product management, only explained the acquisition as a matter of "embracing the Mac community."  He wrote, "Just as with Search Assist, the goal with Inquisitor is to help users find exactly the site they’re looking for as quickly as possible."

Neither Seidman nor Watanabe disclosed how much Inquisitor cost.  A hat tip, in any event, goes to Kristen Nicole.