No Script is a very useful add-on for firefox which allows you to control who gets access to your data:
Here is what Google does with your information:
Here are some alternative search engines:
They cannot however work as well as Google, so if you want to use Google without being tracked use Firefox and download this add-on:
This add-on will show Google random IP adresses so they cannot find out who did the search.
You can enable or disable the add-on on the bottom right of your browser.
And if you use Firefox add this, it will show you EVERY website that secretly tries to steal your information: