If you don't want to see shopping sites in the list of search results, click on "fewer shopping sites" and Google will remove the results from sites like Amazon, BestBuy, eBay. Google also offers the option to see "more shopping sites" in an interface optimized for price comparison.
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If you're logged in to your Google Account and the web history service is enabled, you can restrict the results to the web pages you've already visited. By default, Google Web History only tracks the search results you visit, but you can extend it to your entire browsing history.
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Google's toolbelt starts to become crowded and it's not easily discoverable, but it's a better place for refining results than the advanced search page because you can combine filters and see the results instantly.