I took Google's new Web History for a brief test drive this weekend, using it to save and browse my Google searches. Web History allows me to search my past Google searches chronologically; by topic; and view trends (nice!). Although I'm kind of weirded out that they can track back my past search behavior, both at home and at work.
The features can be expanded to track and display my entire web browsing history, but that gets really creepy.
Thinking ahead to the possibilities (insert evil laugh here), this new capability could allow Google users to opt-in to share their browsing history. In return, users might expect a cut of the revenue (ala Google AdSense), free hosting, free ISP services -- you name it -- giving marketers unheard of visibility into consumer search and browsing behaviors.