Actually, not many are, not surprisingly. iamlost writes:
I have yet to hear a (good) reason for anyone to use it.
But sanity, forum administrator, actually uses it and likes it:
I've used the Google History few times and really appreciated it - which I didn't expect. In both instances it was to find a search I'd done for a site and couldn't remember for the life of me the site's URL. It was a huge help.
Are you using Google Web History? Discuss at Cre8asite Forums.