Social not-working site Facebook is answering Wall Street's demands to make more dosh by coming up with adverts that cyber stalk its customers.
According to Wired, the adverts follow you as you browse the world wide wibble and remember you for longer than your mother.
The Facebook Exchange (FBX) ad-bidding network has been in testing since June.
Advertisers love it. Apparently it delivers the souls of a huge volume of users with a strong propensity to click on ads. It also helps follow those users for longer periods of time than is possible under competing systems. Apparently, it is giving Google a run for its money.
The system is already helping to lift Facebook stock, even though the company has not been saying much about it.
There are several things which could go wrong for Facebook yet. Firstly the system might anger privacy rights groups, particularly in the EU. The other problem is that it is largely PC based and that particularly market appears to be slowly dying off.
On the money making mobile devices, it's harder to follow and retarget users as they routinely switch from browser to apps and back again, and from one device to another.