[breck]

They have. I'm pretty sure Doubleclick does this. Without the CSS hack though(using the cookie method).

The CSS hack is only worthwhile if you don't have the kind of data sources that the big guys have. If this technique actually made money, you would probably want to sign up for something like Lookery or RightMedia because they'd get you better results.

[jjfarren-]

If you read carefully on our website you will learn about the limitations of cookie based methods.