If you belong to ANY Yahoo Groups - be aware that Yahoo is now using "Web Beacons" to track every Yahoo Group user.
It's similar to cookies, but allows Yahoo to record every website and every group you visit, even when you're not connected to Yahoo
Look at their updated privacy statement regarding "relevant advertising" at http://info.yahoo.com/privacy/us/yahoo/Here's the link for removing the web beacons ----------> http://privacy.yahoo.com/privacy/us/beacons/details.html
In that section find "opt-out of interest-matched advertising" link that will let you "opt-out" of their snooping.
Click it and then click the opt-out button on the next page.
*Note that Yahoo's invasion of your privacy (and your ability to opt-out of it) is not user-specific. It is MACHINE specific. That means you will have to opt-out on every computer (and browser) you use