Joost de Valk has created an excellent tool to “depersonalize” search results. It works in Firefox and IE7.

It works by appending &pws=0 to the Google search URL. I tried it on a few searches while logged in to a Google account and there was a very big difference in the search results that I was given.
I don’t think that this will prevent Google from collecting data on you while you are signed in, but it will at least give you the normal SERPs instead of the personalized one.
To prevent Google from associating your searches with your account, you could create separate Firefox profiles and use two different profiles at once — one for Google services, and one for regular browsing.

One Comment
And now it truly works with IE7
and it does google suggest as well.