I just noticed that they still log things even if you delete search
history:
http://www.google.com/history/intl/en/privacyfaq.html
"As is common practice in the industry, Google also maintains a
separate logs system for auditing purposes and to help us improve the
quality of our services for users. For example, we use this
information to audit our ads systems, understand which features are
most popular to users, improve the quality of our search results, and
help us combat vulnerabilities such as denial of service attacks."
Horace Heffner
http://www.mtaonline.net/~hheffner/
