Yes, I have a Google account and have in the past tried out Google Dashboard. What it enables you to do is switch on a function which logs all your web history to the dashboard so you can see all your Google searches, pages you have clicked on from those searches and how long you spent on these pages. This is all part of Google's Analytics Engine, which is used to rank websites. What you must realise however, is that the web history logged by Google Dashboard, is only that which has been passed through Google. In other words, if you visit other websites through other search engines or by keying the addresses directly into the address bar, this history is not logged by Google.
   The web history function can be switched off if you do not want your history logged. However, this is all irrelevant - both Google and your ISP already log everything you do online anyway! Google does it as part of the analytics and your ISP does it via recent amendments to the Communications Data Bill by the current government.
   Google Dashboard merely allows you to view your own history on the website and it can prove useful if you want to recall terms you have searched for and websites you have visited.
   In my opinion, Google has a right to log all Internet activity carried out via its search engine. After all, you are using their service for free. If you use Google Dashboard, this logged information is simply linked to your Google account. But if you use Google anonymously, then your history is still logged against your IP address (the unique Internet address given to you by your ISP when you connect to the Internet). So it's not really anonymous either way.
   However, I strongly disagree with the amendments to the Communications Data Bill which require all ISPs in this country to log and store all your Internet activity (websites visited, key word entered into search engines, emails sent and received and all other Internet-based activity). These amendments were recently brought in by the current Stalinist "Labour" government under the guise of "terror prevention" but in reality, it is simply yet another method of spying on and the controlling of law-abiding citizens by the ever-encroaching "Big Brother" state.
   Therefore, Google Dashboard (and the like) is a moot point as the government in our supposedly free and democratic society has already taken what many consider to be illegal measures to encroach on our civil liberties!
And it's only going to get worse..