Get the feeling you're being watched? You are.

(But not by us.)

The Wall Street Journal recently outed the National Security Agency for collecting massive amounts of data about Americans' internet usage. Including yours.

NSA knows to whom you send e-mails and from whom you receive them. They know the subject lines of those e-mails, the content (if the subject line seemed interesting enough to dig deeper), the sites you visit, the pages you view on those sites and the offers you click on. A government computer knows you're reading this right now.

Sounds spooky 'til you realize Yahoo knew all that a long time ago. When it comes to tracking your online activity, NSA is playing catch up.

The big five internet search/portal/social network companies – Yahoo, Google, Microsoft, AOL and MySpace – record 336 billion data transmissions a month, according to a ComScore study quoted in The New York Times. The most aggressive information gatherer (which is to say the snoopiest of the bunch) is Yahoo. They collect an average of 811 snippets of information about each visitor to their site every month.

That's right. If you've been on Yahoo or one of their partner sites this month, they know 811 things about you. Plus another 811 from last month, and 811 more from every month you visited before that.

Why this intense interest in every single one of us? It's not just voyeurism or national security. It's marketing.