Google can gather a moutain of information on its users. Google keeps a record of every search query you make with the ip address and cookie information. Google does not delete this information, it holds on to it.
All this information is (probably already is) going to be available to law inforcements world wide http://www.siliconvalley.com/mld/sil...y/13657386.htm
Just think about that... Everytime you seacrched for hacking info or p0rn, Google will have the time and date plus the actual words you typed in when you searched for it, This information could be available to even a lowly local sherif in the not too distant future. It will definitely be available to Feds.
So when ever I am searching for something I would not want every cop to know about I use www.scroogle.org
It does not track you like google but you still get to use it's google's search engine... check it out
P.S I know you can use proxies or tor, but there slow and a hassle to be using all the time.