Google, building on their search foundation, is developing a new personalized search enhancement that, though still in beta, is worth taking a look:
Google Personalized Search - for getting the results most relevant to you. Basically, it maintains a history of your searches, ordering your results based on your accumulating history and improving over time. You can control when you want searches to count in your history or when you want the results ignored (Pause/Resume).
The image below is the initial (empty) history page you will see after you first log in (it requires a Google account). 
After you set up your personalized search it will only be in effect when you are logged into your account (or when you are not in "Pause" mode).
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