I read today: Facebook Tests Software to Track Your Cursor on Screen. So Facebook has terrifying new software to let them know where your mouse moves...
<tr><td>Cursor X:</td><td id="crsx"></td></tr>
<tr><td>Cursor Y:</td><td id="crsy"></td></tr>
document.getElementById("crsx").innerHTML = n.pageX;
document.getElementById("crsy").innerHTML = n.pageY;
From there it's simply a matter of keeping track of the X and the Y of all of your page elements; easily be done through smart CSS, and then pushing the location-mapped identities to the database every (n) number of times a second. Here's another method tracking by using the onMouseOver event on an ad:
You like Doritos. <div id="crsz"></div>
doritos.onMouseOver = mouseOver;
var count = 0;
document.getElementById("crsz").innerHTML = count+" Times";
Companies like Facebook and Google started out with such positive energies; remember Google's Don't be Evil corporate motto? Today these companies are finding themselves no longer happy to just exist and make the world a better place, but they need revenue to stay as huge as they are, and that means finding ways to use all of that data that users create.