1. Go to the address
CODEhttp://privacy.yahoo.com/privacy
and click the "Cookies" link under the "Special Topics" column.
2. Click the "Web Beacons" link under the "Reference Links" Column.
3. On this page, click the "click here to opt out" link toward the end of the third paragraph under the "Outside the Yahoo! Network" title.
4. After a while, a page that says you have been out of the monitoring program will load. Without doing anything, close that page or continue your usual surfing by typing another address in the address bar. (Do NOT click the "Cancel Opt-out" button, your action will be cancelled!)
5. You’re done! Now Yahoo! will not record what you’re doing during surfing.
You can let your friends that might be interested know about this; since no matter how "innocent" it may seem, it’s still a violation of privacy