It's All Okay Until It Starts Costing You Money

(Get it? It's supposed to be Oedipus.)

In case you'd gotten the idea that protecting your online privacy was only for the Paranoid, looky here! That tracking is actually costing you money:

http://www.washingtonpost.com/wp-dyn/content/article/2010/12/11/AR2010121102435.html

In its most brazen form, it works like this: Retailers read the cookies kept on your browser or glean information from your past purchase history when you are logged into a site. That gives them a sense of what you search for and buy, how much you paid for it, and whether you might be willing and able to spend more.

They alter their prices or offers accordingly. Consumers - in the few cases they recognize it is going on, by shopping in two browsers simultaneously, for instance - tend to go apoplectic. But the practice is perfectly legal, and increasingly common - pervasive, even, for some products.

Banks do the same for products such as mortgages and credit cards, where prices change depending on everything from the customer's credit rating to the manager's whims to what browser the searcher uses. This August, the Wall Street Journal reported on a company that helps Capital One determine what credit-card deals to offer customers when they land at the site.Sellers of time-sensitive, highly price-variable goods (think airline tickets, hotel rooms, or car rentals) do it all the time, somewhat openly. If you have ever had the annoying experience of buying a plane ticket through a portal such as Kayak, then seeing the final price jump $10 or $40 at check out, you have probably found yourself on the receiving end of dynamic pricing.

Here's one way to start protecting yourself, but there's much more you can-- and should-- be doing. Keeping yourself signed out of Facebook and Google  unless you are using that page right then, and then deleting all cookies when you close your browser is the least you can do.