In order to efficiently target their ads based on each user's search habits, Google keeps track of every search submitted. Even with Firefox's AdBlock Plus (one of the best FF's add-ins), Google still keeps our search records in their servers. I don't know if there's a way to completely avoid this (my guess is no), but at least Google offers a way to opt-put from their targeted ads. From Lifehacker:
Opt Out of Google's Targeted Ads
Google recently announced an
ad-targeting system that tracks where you go on the web, and tailors future ads to your interests. Creeped out? You've got a few ways out of the observation tank.
While the Electronic Frontier Foundation
explains, pretty wisely, that the smartest move would have been to let
Google's many users opt
in to supposedly "better" ads, market forces mean that's just not going to happen. Still, Google does
explain how it works, and gives you a preference, and a browser plug-in, that can keep behavior-snooping bots at bay.
Log into your Google account and mozy over to the
Google Ads Preferences page, where you can hit an Opt Out button to put a cookie (identified and detailed) on your system that blocks ad monitoring and targeting. The downside, though, is that any time you wipe out your cookies (a pretty common move, especially amongst the privacy-conscious), that preference washes out with them. So Google also offers a
Opt-Out Preferences plug-in for
Internet Explorer and Firefox that auto-kills ad targeting. Good for those who use those two leaders of the market; kinda annoying for everyone else.
(
more)
So basically Google offers two ways to op-out from these ads: using a preferences cookie (temporal solution) and installing a plug-in in Firefox and IE. It's not a perfect solution but it's something. The Preferences and Plug-in can be found here: Advertising Cookie Opt-out Plugin.
Edit: I just noticed that the link has additional instructions for Chrome and Safari.
[Edited at 2009-03-17 16:41 GMT]