You might not know that Facebook has more than 200 ways of tracking its users around the web.

AdAge says Facebook's advertising tool applies a hashtag to terms such as "morning sickness," "ultrasound" and "pregnancy test" and can then serve ads against them.

THIS IS FREAKING CREEPY:

Café Mom VP-Marketing Kristina Tipton said her team has identified a Facebook audience of more than a million women who are likely to be pregnant or may have recently been so by anonymously targeting specific keywords that show up in users' conversations ... Ms. Tipton has been told by her Facebook rep that this process includes people who have mentioned the terms in their posts as well as users who have added those terms to their profile.

STOP IT FACEBOOK. STOP IT NOW!!

If this results in ads more relevant to its users, is this worse than Google showing pregnancy-related ads when someone searches for [pregnancy test]? (I suspect Google's policies would even allow that one-time revealed-preference to affect future ad presentations elsewhere as well.)

And Charles Duhigg's February NYTimes magazine story about Target showed even offline retailers have similar pregnancy-targeting capabilities.

What's the bright line rule that Facebook (or others) should use to know when using freely-offered information shouldn't be used for ad-targeting?

Google uses your search keywords on Google properties, not the whole Web.

Facebook uses a mix of Javascript, iframes, images, and cookies all over the Web.

Facebook's net-net is hundreds of trackers that watch what you read, click on, and buy.

Why not let the pregnancy ads be opt-in instead of spying on someone's web surfing?

Google has sensors of web visits everywhere via Analytics, AdSense/Doubleclick, other inserts (like their free hosting of static resources or +1 buttons) and from Google Toolbar users. I suspect Google thus has far more coverage and clicktrail data than Facebook. And of course Google was recently fined for circumventing Safari's third-party-cookie controls, as part of one of their advertising inserts.

Is there a clear standard that all companies doing the same thing could follow to know what's allowed?

(Also, the pregnancy-triggers originally mentioned seemed to be off of textual content people voluntarily entered at Facebook, not offsite clicktrails... that sounds a lot like Google's triggering off searches and GMail content. I'd say either both are creepy/over-the-line or neither is.)

There is not a clear standard.

I believe that one day there will be.

Someone just needs to lead. :)