Install this Firefox extension and you’re good to go. You can now stay signed into your Google account while searching, without Google knowing that it’s you. Here’s how it works, according to the developer:
When installed no tracking cookies are sent to Google while searching. This is done by blocking certain Google cookies (such as the PREF-ID) or generating randomized ones (which are worthless for tracking). Other cookies that just contain your search preferences will be allowed, so your preferences are preserved. You will stay logged in on other Google services such as Youtube or Gmail. It also removes ads and clutter from the Google main page that is normally shown when cookies are disabled.
That’s right, the added bonus of Searchonymous is that the ads you normally see in Google results are now gone! It doesn’t always work, but you’ll usually get an ad-free experience. Pretty neat for a free app, right?