In the new digital world, we are the sum of our trackable behavior. The web sites we read, the items we share, the products we buy, are all elements that contribute to our digital personas. Online marketers desperately want to collect our behavioral data so they can analyze our history, better target their offers, and maybe even predict our next moves. But the question remains, do we want them to have access? Do we trust their intentions? And, more importantly, if we don't, can we stop them from peering over our shoulders as we navigate our digital lives?