Yahoo And Google Now Let You Opt Out Of Ads (Because It’s Better Than Letting You Opt In)
techcrunch.com
techcrunch.com
While I would not mind being shown ads I care about, I worry about the cost. I don't want companies to be able to share detailed click trails and be able to produce in depth biographies because of the potential for abuse, be it governmental, corporate or "hm I wonder what I can find out about that girl I met yesterday".
PS: as an addendum, I know people with Google log access, and while it's less scary than it sounds, I know there are "tons" of people with such access... and counterparts at other companies. I don't know if I can trust all those people with knowing when I get funny rashes or whatever.